Version:            (using KDE 4.1.3)
Compiler:          gcc version 4.1.2 (Gentoo 4.1.2 p1.1)  
OS:                Linux
Installed from:    Gentoo Packages

System: Linux jern 2.6.26-gentoo-r4 #1 SMP Fri Jan 2 14:49:52 CET 2009 x86_64 AMD Athlon(tm) 64 X2 Dual Core Processor 5000+ AuthenticAMD GNU/Linux
Graphics card: 01:00.0 VGA compatible controller: ATI Technologies Inc Device 9505
X.Org X Server 1.5.3
Crash occurs with both fglrx and radeonhd drivers.

Crash occurs every time when loading kde from kdm. When removing plasma.desktop from autostart, kwin starts. Most applications works fine, and i can then launch plasma. When plasma is launched, left clicking on start menu or right clicking on background immediately causes a crash. .xession-errors report: kwin: Fatal IO error: client killed

Another application causing the same crash is Terminal.

Both Terminal and plasma can be started and neither is crashing when using Xfce as window manager.

Following is backtrace after crashing terminal and plasma (I've truncated the verbose versions):
Terminal:
(gdb) bt
#0  0x00000000004d7193 in miHandleValidateExposures (pWin=0x1623e50) at miwindow.c:453
#1  0x0000000000435dda in UnmapWindow (pWin=0x16b9040, fromConfigure=0) at window.c:3062
#2  0x00000000004eea4c in compFreeClientWindow (pWin=0x16b9040, id=147) at compalloc.c:206
#3  0x00000000004ec319 in FreeCompositeClientWindow (value=0xffdcdad500000000, ccwid=2702462776) at compext.c:93
#4  0x0000000000433016 in FreeResource (id=147, skipDeleteFuncType=0) at resource.c:561
#5  0x00000000004ee7ee in compUnredirectWindow (pClient=0x7c81e0, pWin=<value optimized out>, update=0) at compalloc.c:256
#6  0x00000000004ecd2f in compChangeWindowAttributes (pWin=0x16b9040, mask=64) at compinit.c:128
#7  0x00000000004d76a8 in miCheckSubSaveUnder (pParent=0x16b9040, pFirst=<value optimized out>, pRegion=0x7fffab7a13e0) at miwindow.c:226
#8  0x00000000004d75cb in miCheckSubSaveUnder (pParent=0x1623e50, pFirst=<value optimized out>, pRegion=0x7fffab7a1440) at miwindow.c:193
#9  0x00000000004d75cb in miCheckSubSaveUnder (pParent=0x839ab0, pFirst=<value optimized out>, pRegion=0x7fffab7a1490) at miwindow.c:193
#10 0x00000000004d773e in miChangeSaveUnder (pWin=<value optimized out>, first=0x7f59a1144f38) at miwindow.c:273
#11 0x0000000000436316 in MapWindow (pWin=0x16564e0, client=<value optimized out>) at window.c:2806
#12 0x0000000000448426 in ProcMapWindow (client=0x1654b70) at dispatch.c:695
#13 0x0000000000448bf4 in Dispatch () at dispatch.c:454
#14 0x0000000000431627 in main (argc=9, argv=0x7fffab7a16c8, envp=<value optimized out>) at main.c:441

#0  0x00000000004d7193 in miHandleValidateExposures (pWin=0x1623e50) at miwindow.c:453
        pChild = (WindowPtr) 0x1624180
        val = (ValidatePtr) 0x1659f40
        WindowExposures = (WindowExposuresProcPtr) 0x4c287c <miWindowExposures>
#1  0x0000000000435dda in UnmapWindow (pWin=0x16b9040, fromConfigure=0) at window.c:3062
        pParent = <value optimized out>
        event = {u = {u = {type = 224 '�', detail = 158 '\236', sequenceNumber = 357}, keyButtonPointer = {pad00 = 23437024, time = 0, root = 2704755040, event = 32601,
      child = 23826496, rootX = 0, rootY = 0, eventX = 147, eventY = 0, state = 0, sameScreen = 0 '\0', pad1 = 0 '\0'}, enterLeave = {pad00 = 23437024, time = 0,
      root = 2704755040, event = 32601, child = 23826496, rootX = 0, rootY = 0, eventX = 147, eventY = 0, state = 0, mode = 0 '\0', flags = 0 '\0'}, focus = {
      pad00 = 23437024, window = 0, mode = 96 '`', pad1 = 73 'I', pad2 = 55 '7', pad3 = 161 '�'}, expose = {pad00 = 23437024, window = 0, x = 18784, y = 41271,
      width = 32601, height = 0, count = 36928, pad2 = 363}, graphicsExposure = {pad00 = 23437024, drawable = 0, x = 18784, y = 41271, width = 32601, height = 0,
      minorEvent = 36928, count = 363, majorEvent = 0 '\0', pad1 = 0 '\0', pad2 = 0 '\0', pad3 = 0 '\0'}, noExposure = {pad00 = 23437024, drawable = 0,
      minorEvent = 18784, majorEvent = 55 '7', bpad = 161 '�'}, visibility = {pad00 = 23437024, window = 0, state = 96 '`', pad1 = 73 'I', pad2 = 55 '7',
      pad3 = 161 '�'}, createNotify = {pad00 = 23437024, parent = 0, window = 2704755040, x = 32601, y = 0, width = 36928, height = 363, borderWidth = 0,
      override = 0 '\0', bpad = 0 '\0'}, destroyNotify = {pad00 = 23437024, event = 0, window = 2704755040}, unmapNotify = {pad00 = 23437024, event = 0,
      window = 2704755040, fromConfigure = 89 'Y', pad1 = 127 '\177', pad2 = 0 '\0', pad3 = 0 '\0'}, mapNotify = {pad00 = 23437024, event = 0, window = 2704755040,
      override = 89 'Y', pad1 = 127 '\177', pad2 = 0 '\0', pad3 = 0 '\0'}, mapRequest = {pad00 = 23437024, parent = 0, window = 2704755040}, reparent = {
      pad00 = 23437024, event = 0, window = 2704755040, parent = 32601, x = -28608, y = 363, override = 0 '\0', pad1 = 0 '\0', pad2 = 0 '\0', pad3 = 0 '\0'},
    configureNotify = {pad00 = 23437024, event = 0, window = 2704755040, aboveSibling = 32601, x = -28608, y = 363, width = 0, height = 0, borderWidth = 147,
      override = 0 '\0', bpad = 0 '\0'}, configureRequest = {pad00 = 23437024, parent = 0, window = 2704755040, sibling = 32601, x = -28608, y = 363, width = 0,
      height = 0, borderWidth = 147, valueMask = 0, pad1 = 0}, gravity = {pad00 = 23437024, event = 0, window = 2704755040, x = 32601, y = 0, pad1 = 23826496, pad2 = 0,
      pad3 = 147, pad4 = 0}, resizeRequest = {pad00 = 23437024, window = 0, width = 18784, height = 41271}, circulate = {pad00 = 23437024, event = 0,
      window = 2704755040, parent = 32601, place = 64 '@', pad1 = 144 '\220', pad2 = 107 'k', pad3 = 1 '\001'}, property = {pad00 = 23437024, window = 0,
      atom = 2704755040, time = 32601, state = 64 '@', pad1 = 144 '\220', pad2 = 363}, selectionClear = {pad00 = 23437024, time = 0, window = 2704755040, atom = 32601},
    selectionRequest = {pad00 = 23437024, time = 0, owner = 2704755040, requestor = 32601, selection = 23826496, target = 0, property = 147}, selectionNotify = {
      pad00 = 23437024, time = 0, requestor = 2704755040, selection = 32601, target = 23826496, property = 0}, colormap = {pad00 = 23437024, window = 0,
      colormap = 2704755040, new = 89 'Y', state = 127 '\177', pad1 = 0 '\0', pad2 = 0 '\0'}, mappingNotify = {pad00 = 23437024, request = 0 '\0', firstKeyCode = 0 '\0',
      count = 0 '\0', pad1 = 0 '\0'}, clientMessage = {pad00 = 23437024, window = 0, u = {l = {type = 2704755040, longs0 = 32601, longs1 = 23826496, longs2 = 0,
          longs3 = 147, longs4 = 0}, s = {type = 2704755040, shorts0 = 32601, shorts1 = 0, shorts2 = -28608, shorts3 = 363, shorts4 = 0, shorts5 = 0, shorts6 = 147,
          shorts7 = 0, shorts8 = 0, shorts9 = 0}, b = {type = 2704755040, bytes = "Y\177\000\000@\220k\001\000\000\000\000\223\000\000\000\000\000\000"}}}}}
        pScreen = (ScreenPtr) 0x811eb0
        pLayerWin = (WindowPtr) 0x16b9040
#2  0x00000000004eea4c in compFreeClientWindow (pWin=0x16b9040, id=147) at compalloc.c:206
        cw = (CompWindowPtr) 0x1625ab0
        ccw = <value optimized out>
        prev = <value optimized out>
#3  0x00000000004ec319 in FreeCompositeClientWindow (value=0xffdcdad500000000, ccwid=2702462776) at compext.c:93
No locals.

plasma:
(gdb) bt
#0  0x00000000004d7193 in miHandleValidateExposures (pWin=0x839ab0) at miwindow.c:453
#1  0x0000000000435dda in UnmapWindow (pWin=0x1630b10, fromConfigure=0) at window.c:3062
#2  0x00000000004eea4c in compFreeClientWindow (pWin=0x1630b10, id=142) at compalloc.c:206
#3  0x00000000004ec319 in FreeCompositeClientWindow (value=0x312d393500312d39, ccwid=2108608312) at compext.c:93
#4  0x0000000000433016 in FreeResource (id=142, skipDeleteFuncType=0) at resource.c:561
#5  0x00000000004ee7ee in compUnredirectWindow (pClient=0x7c81e0, pWin=<value optimized out>, update=0) at compalloc.c:256
#6  0x00000000004ecd2f in compChangeWindowAttributes (pWin=0x1630b10, mask=64) at compinit.c:128
#7  0x00000000004d76a8 in miCheckSubSaveUnder (pParent=0x1630b10, pFirst=<value optimized out>, pRegion=0x7fff881482a0) at miwindow.c:226
#8  0x00000000004d75cb in miCheckSubSaveUnder (pParent=0x839ab0, pFirst=<value optimized out>, pRegion=0x7fff881482f0) at miwindow.c:193
#9  0x00000000004d773e in miChangeSaveUnder (pWin=<value optimized out>, first=0x7f337daecf38) at miwindow.c:273
#10 0x0000000000436316 in MapWindow (pWin=0x1285140, client=<value optimized out>) at window.c:2806
#11 0x0000000000448426 in ProcMapWindow (client=0x8759e0) at dispatch.c:695
#12 0x0000000000448bf4 in Dispatch () at dispatch.c:454
#13 0x0000000000431627 in main (argc=9, argv=0x7fff88148528, envp=<value optimized out>) at main.c:441

#0  0x00000000004d7193 in miHandleValidateExposures (pWin=0x839ab0) at miwindow.c:453
        pChild = (WindowPtr) 0x1285140
        val = (ValidatePtr) 0x127c950
        WindowExposures = (WindowExposuresProcPtr) 0x4c287c <miWindowExposures>
#1  0x0000000000435dda in UnmapWindow (pWin=0x1630b10, fromConfigure=0) at window.c:3062
        pParent = <value optimized out>
        event = {u = {u = {type = 0 '\0', detail = 0 '\0', sequenceNumber = 0}, keyButtonPointer = {pad00 = 0, time = 0, root = 2110900576, event = 32563,
      child = 23268112, rootX = 0, rootY = 0, eventX = 142, eventY = 0, state = 0, sameScreen = 0 '\0', pad1 = 0 '\0'}, enterLeave = {pad00 = 0, time = 0,
      root = 2110900576, event = 32563, child = 23268112, rootX = 0, rootY = 0, eventX = 142, eventY = 0, state = 0, mode = 0 '\0', flags = 0 '\0'}, focus = {pad00 = 0,
      window = 0, mode = 96 '`', pad1 = 201 '�', pad2 = 209 '�', pad3 = 125 '}'}, expose = {pad00 = 0, window = 0, x = 51552, y = 32209, width = 32563, height = 0,
      count = 2832, pad2 = 355}, graphicsExposure = {pad00 = 0, drawable = 0, x = 51552, y = 32209, width = 32563, height = 0, minorEvent = 2832, count = 355,
      majorEvent = 0 '\0', pad1 = 0 '\0', pad2 = 0 '\0', pad3 = 0 '\0'}, noExposure = {pad00 = 0, drawable = 0, minorEvent = 51552, majorEvent = 209 '�',
      bpad = 125 '}'}, visibility = {pad00 = 0, window = 0, state = 96 '`', pad1 = 201 '�', pad2 = 209 '�', pad3 = 125 '}'}, createNotify = {pad00 = 0, parent = 0,
      window = 2110900576, x = 32563, y = 0, width = 2832, height = 355, borderWidth = 0, override = 0 '\0', bpad = 0 '\0'}, destroyNotify = {pad00 = 0, event = 0,
      window = 2110900576}, unmapNotify = {pad00 = 0, event = 0, window = 2110900576, fromConfigure = 51 '3', pad1 = 127 '\177', pad2 = 0 '\0', pad3 = 0 '\0'},
    mapNotify = {pad00 = 0, event = 0, window = 2110900576, override = 51 '3', pad1 = 127 '\177', pad2 = 0 '\0', pad3 = 0 '\0'}, mapRequest = {pad00 = 0, parent = 0,
      window = 2110900576}, reparent = {pad00 = 0, event = 0, window = 2110900576, parent = 32563, x = 2832, y = 355, override = 0 '\0', pad1 = 0 '\0', pad2 = 0 '\0',
      pad3 = 0 '\0'}, configureNotify = {pad00 = 0, event = 0, window = 2110900576, aboveSibling = 32563, x = 2832, y = 355, width = 0, height = 0, borderWidth = 142,
      override = 0 '\0', bpad = 0 '\0'}, configureRequest = {pad00 = 0, parent = 0, window = 2110900576, sibling = 32563, x = 2832, y = 355, width = 0, height = 0,
      borderWidth = 142, valueMask = 0, pad1 = 0}, gravity = {pad00 = 0, event = 0, window = 2110900576, x = 32563, y = 0, pad1 = 23268112, pad2 = 0, pad3 = 142,
      pad4 = 0}, resizeRequest = {pad00 = 0, window = 0, width = 51552, height = 32209}, circulate = {pad00 = 0, event = 0, window = 2110900576, parent = 32563,
      place = 16 '\020', pad1 = 11 '\v', pad2 = 99 'c', pad3 = 1 '\001'}, property = {pad00 = 0, window = 0, atom = 2110900576, time = 32563, state = 16 '\020',
      pad1 = 11 '\v', pad2 = 355}, selectionClear = {pad00 = 0, time = 0, window = 2110900576, atom = 32563}, selectionRequest = {pad00 = 0, time = 0,
      owner = 2110900576, requestor = 32563, selection = 23268112, target = 0, property = 142}, selectionNotify = {pad00 = 0, time = 0, requestor = 2110900576,
      selection = 32563, target = 23268112, property = 0}, colormap = {pad00 = 0, window = 0, colormap = 2110900576, new = 51 '3', state = 127 '\177', pad1 = 0 '\0',
      pad2 = 0 '\0'}, mappingNotify = {pad00 = 0, request = 0 '\0', firstKeyCode = 0 '\0', count = 0 '\0', pad1 = 0 '\0'}, clientMessage = {pad00 = 0, window = 0, u = {
        l = {type = 2110900576, longs0 = 32563, longs1 = 23268112, longs2 = 0, longs3 = 142, longs4 = 0}, s = {type = 2110900576, shorts0 = 32563, shorts1 = 0,
          shorts2 = 2832, shorts3 = 355, shorts4 = 0, shorts5 = 0, shorts6 = 142, shorts7 = 0, shorts8 = 0, shorts9 = 0}, b = {type = 2110900576,
          bytes = "3\177\000\000\020\vc\001\000\000\000\000\216\000\000\000\000\000\000"}}}}}
        pScreen = (ScreenPtr) 0x811eb0
        pLayerWin = (WindowPtr) 0x1630b10
#2  0x00000000004eea4c in compFreeClientWindow (pWin=0x1630b10, id=142) at compalloc.c:206
        cw = (CompWindowPtr) 0x16307b0
        ccw = <value optimized out>
        prev = <value optimized out>
#3  0x00000000004ec319 in FreeCompositeClientWindow (value=0x312d393500312d39, ccwid=2108608312) at compext.c:93
No locals.

A post on the gentoo forum regarding the problem is here: http://forums.gentoo.org/viewtopic-t-722636.html