Version:           1.8.50 (using KDE 3.4.89 (>= 20050615), compiled sources)
Compiler:          gcc version 3.4.1 (Mandrakelinux 10.1 3.4.1-4mdk)
OS:                Linux (i686) release 2.6.8.1-12mdk

After using the systray icon for a while it will disapper and then when launching kontact from the menu (since it's not in the taskbar or systray) a crash dialod will appear. 
To reproduce

1. Open kontact.
2. Click on Mail
3. Go to Help -> KMail introdcution
4. Click the link that says "documentation" 
5. After konqueror launches go back to kontact and close it using the X in the window decoration.
6. Click on the systray icon to bring it back.
7. Close it using the X in the window decration. 
8. Repeat 6 and 7 until the systray icon disappears. It's taken as many as 10 clicks on the systray and as little as 4 (when using this method) to have this happen
9. Once the systray icon is gone Use the Kmenu to launch kontact. The crash dialog should come up. 

bt:
Using host libthread_db library "/lib/tls/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 1117970944 (LWP 9690)]
[KCrash handler]
#7  0xffffe410 in ?? ()
#8  0xbfffecf0 in ?? ()
#9  0x00000006 in ?? ()
#10 0x000025da in ?? ()
#11 0x420ec805 in raise () from /lib/tls/libc.so.6
#12 0x420ee1e9 in abort () from /lib/tls/libc.so.6
#13 0x420e5f01 in __assert_fail () from /lib/tls/libc.so.6
#14 0x413baeec in KCmdLineArgs::isSet (this=0x807fa70,
    _opt=0x806c048 "module") at kcmdlineargs.cpp:1184
#15 0x0805c6f1 in KontactApp::newInstance (this=0xbffff590) at main.cpp:110
#16 0x413a709d in KUniqueApplication::processDelayed (this=0xbffff590)
    at kuniqueapplication.cpp:444
#17 0x413a7489 in KUniqueApplication::qt_invoke (this=0xbffff590, _id=18,
    _o=0xbffff070) at kuniqueapplication.moc:86
#18 0x41849bf7 in QObject::activate_signal (this=0x8156a30, clist=0x88951e8,
    o=0xbffff070) at kernel/qobject.cpp:2355
#19 0x41bae4e0 in QSignal::signal (this=0x8156a30, t0=@0x8156a58)
    at .moc/debug-shared-mt/moc_qsignal.cpp:100
#20 0x41867b89 in QSignal::activate (this=0x8156a30) at kernel/qsignal.cpp:212
#21 0x4186fb0b in QSingleShotTimer::event (this=0x8156a08)
    at kernel/qtimer.cpp:286
#22 0x417e5391 in QApplication::internalNotify (this=0xbffff590,
    receiver=0x8156a08, e=0xbffff2f0) at kernel/qapplication.cpp:2635
#23 0x417e4855 in QApplication::notify (this=0xbffff590, receiver=0x8156a08,
    e=0xbffff2f0) at kernel/qapplication.cpp:2358
#24 0x412f4663 in KApplication::notify (this=0xbffff590, receiver=0x8156a08,
    event=0xbffff2f0) at kapplication.cpp:549
#25 0x4060b877 in QApplication::sendEvent (receiver=0x8156a08,
    event=0xbffff2f0) at qapplication.h:491
#26 0x417d3129 in QEventLoop::activateTimers (this=0x80ab070)
    at kernel/qeventloop_unix.cpp:556
#27 0x4178b98d in QEventLoop::processEvents (this=0x80ab070, flags=4)
    at kernel/qeventloop_x11.cpp:389
#28 0x417fa338 in QEventLoop::enterLoop (this=0x80ab070)
    at kernel/qeventloop.cpp:198
#29 0x417fa256 in QEventLoop::exec (this=0x80ab070)
    at kernel/qeventloop.cpp:145
#30 0x417e5511 in QApplication::exec (this=0xbffff590)
    at kernel/qapplication.cpp:2758
#31 0x0805cb71 in main (argc=1, argv=0xbffff764) at main.cpp:177