Version:           1.9.7 (using KDE 3.5.7, Debian Package 4:3.5.7.dfsg.1-7 (lenny/sid))
Compiler:          Target: i486-linux-gnu
OS:                Linux (i686) release 2.6.18-4-686

I tried moving a mail folder from an IMAP account to a local folder and KMail crashed with the following backtrace:

Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1243322688 (LWP 3516)]
[New Thread -1289774192 (LWP 3520)]
[New Thread -1281385584 (LWP 3519)]
[New Thread -1272996976 (LWP 3518)]
[New Thread -1264608368 (LWP 3517)]
[KCrash handler]
#5  0xb770cff1 in fileno_unlocked () from /lib/libc.so.6
#6  0xb4f448e8 in KMFolderIndex::writeIndex (this=0x873e028, 
    createEmptyIndex=false)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfolderindex.cpp:202
#7  0xb4e6290c in KMFolderMbox::create (this=0x873e028)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldermbox.cpp:252
#8  0xb4dc06f7 in KMFolder (this=0x86e7eb0, aParent=0x84dc370, 
    aFolderName=@0xbfa60a20, aFolderType=KMFolderTypeMbox, withIndex=true, 
    exportedSernums=true)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfolder.cpp:81
#9  0xb4dfcb41 in KMFolderDir::createFolder (this=0x84dc370, 
    aFolderName=@0xbfa60a20, aSysFldr=false, aFolderType=KMFolderTypeMbox)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfolderdir.cpp:104
#10 0xb4dfef58 in KMFolderMgr::createFolder (this=0x8431d50, 
    fName=@0xbfa60a20, sysFldr=false, aFolderType=KMFolderTypeMbox, 
    aFolderDir=0x84dc370)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldermgr.cpp:183
#11 0xb500cfec in KMail::CopyFolderJob::createTargetDir (this=0x87428a0)
    at /build/buildd/kdepim-3.5.7/./kmail/copyfolderjob.cpp:211
#12 0xb500db52 in KMail::CopyFolderJob::execute (this=0x87428a0)
    at /build/buildd/kdepim-3.5.7/./kmail/copyfolderjob.cpp:71
#13 0xb4fc36d3 in KMail::RenameJob::execute (this=0x887fc70)
    at /build/buildd/kdepim-3.5.7/./kmail/renamejob.cpp:95
#14 0xb4f4bb8d in KMail::FolderJob::start (this=0x0)
    at /build/buildd/kdepim-3.5.7/./kmail/folderjob.cpp:110
#15 0xb4dfe1b3 in KMFolderMgr::renameFolder (this=0x8431d50, 
    folder=0x8443808, newName=@0xbfa60bf8, newParent=0x84dc370)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldermgr.cpp:540
#16 0xb4dff089 in KMFolderMgr::moveFolder (this=0x8431d50, folder=0x8443808, 
    newParent=0x84dc370)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldermgr.cpp:530
#17 0xb4d66d48 in KMFolderTree::moveOrCopyFolder (this=0x8597b70, 
    sources=@0xbfa60cd8, destination=0x84857f0, move=true)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldertree.cpp:2032
#18 0xb4d67064 in KMFolderTree::moveSelectedToFolder (this=0x8597b70, 
    menuId=-4265) at /build/buildd/kdepim-3.5.7/./kmail/kmfoldertree.cpp:1926
#19 0xb4d6c8b2 in KMFolderTree::qt_invoke (this=0x8597b70, _id=143, 
    _o=0xbfa60da0) at ./kmfoldertree.moc:516
#20 0xb6f4fc3d in QObject::activate_signal (this=0x8741d18, clist=0x8837920, 
    o=0xbfa60da0) at kernel/qobject.cpp:2380
#21 0xb6f5045d in QObject::activate_signal (this=0x8741d18, signal=2, 
    param=-4265) at kernel/qobject.cpp:2449
#22 0xb72fc847 in QPopupMenu::activated (this=0x8741d18, t0=-4265)
    at .moc/debug-shared-mt/moc_qpopupmenu.cpp:151
#23 0xb7074004 in QPopupMenu::actSig (this=0x8741d18, id=-4265, 
    inwhatsthis=false) at widgets/qpopupmenu.cpp:729
#24 0xb70745df in QPopupMenu::mouseReleaseEvent (this=0x8741d18, e=0xbfa612e4)
    at widgets/qpopupmenu.cpp:1695
#25 0xb6f86460 in QWidget::event (this=0x8741d18, e=0xbfa612e4)
    at kernel/qwidget.cpp:4702
#26 0xb6ee436a in QApplication::internalNotify (this=0xbfa626e8, 
    receiver=0x8741d18, e=0xbfa612e4) at kernel/qapplication.cpp:2635
#27 0xb6ee6522 in QApplication::notify (this=0xbfa626e8, receiver=0x8741d18, 
    e=0xbfa612e4) at kernel/qapplication.cpp:2421
#28 0xb7625ff2 in KApplication::notify (this=0xbfa626e8, receiver=0x8741d18, 
    event=0xbfa612e4)
    at /build/buildd/kdelibs-3.5.7.dfsg.1/./kdecore/kapplication.cpp:550
#29 0xb6e7573d in QApplication::sendSpontaneousEvent (receiver=0x8741d18, 
    event=0xbfa612e4) at kernel/qapplication.h:523
#30 0xb6e74144 in QETWidget::translateMouseEvent (this=0x8741d18, 
    event=0xbfa616e8) at kernel/qapplication_x11.cpp:4243
#31 0xb6e72858 in QApplication::x11ProcessEvent (this=0xbfa626e8, 
    event=0xbfa616e8) at kernel/qapplication_x11.cpp:3478
#32 0xb6e8967c in QEventLoop::processEvents (this=0x80ab0a8, flags=4)
    at kernel/qeventloop_x11.cpp:192
#33 0xb6eff6e4 in QEventLoop::enterLoop (this=0x80ab0a8)
    at kernel/qeventloop.cpp:198
#34 0xb6ee5e91 in QApplication::enter_loop (this=0xbfa626e8)
    at kernel/qapplication.cpp:2793
#35 0xb7075463 in QPopupMenu::exec (this=0x873b758, pos=@0xbfa61bac, 
    indexAtPoint=0) at widgets/qpopupmenu.cpp:2452
#36 0xb4d6ace5 in KMFolderTree::slotContextMenuRequested (this=0x8597b70, 
    lvi=0x872eb90, p=@0xbfa61bac)
    at /build/buildd/kdepim-3.5.7/./kmail/kmfoldertree.cpp:1134
#37 0xb4d6c860 in KMFolderTree::qt_invoke (this=0x8597b70, _id=140, 
    _o=0xbfa61ae0) at ./kmfoldertree.moc:513
#38 0xb6f4fb10 in QObject::activate_signal (this=0x8597b70, clist=0x859c170, 
    o=0xbfa61ae0) at kernel/qobject.cpp:2356
#39 0xb72f8a56 in QListView::contextMenuRequested (this=0x8597b70, 
    t0=0x872eb90, t1=@0xbfa61bac, t2=0)
    at .moc/debug-shared-mt/moc_qlistview.cpp:515
#40 0xb704c644 in QListView::contentsContextMenuEvent (this=0x8597b70, 
    e=0xbfa61bf0) at widgets/qlistview.cpp:4452
#41 0xb7083d46 in QScrollView::viewportContextMenuEvent (this=0x8597b70, 
    e=0xbfa62204) at widgets/qscrollview.cpp:1886
#42 0xb7085afe in QScrollView::eventFilter (this=0x8597b70, obj=0x85984b0, 
    e=0xbfa62204) at widgets/qscrollview.cpp:1543
#43 0xb704dbc0 in QListView::eventFilter (this=0x8597b70, o=0x85984b0, 
    e=0xbfa62204) at widgets/qlistview.cpp:3866
#44 0xb4d64cd9 in KMFolderTree::eventFilter (this=0x8597b70, o=0x85984b0, 
    e=0xbfa62204) at /build/buildd/kdepim-3.5.7/./kmail/kmfoldertree.cpp:1732
#45 0xb6f4d89e in QObject::activate_filters (this=0x85984b0, e=0xbfa62204)
    at kernel/qobject.cpp:903
#46 0xb6f4d91c in QObject::event (this=0x85984b0, e=0xbfa62204)
    at kernel/qobject.cpp:735
#47 0xb6f86380 in QWidget::event (this=0x85984b0, e=0xbfa62204)
    at kernel/qwidget.cpp:4678
#48 0xb6ee436a in QApplication::internalNotify (this=0xbfa626e8, 
    receiver=0x85984b0, e=0xbfa62204) at kernel/qapplication.cpp:2635
#49 0xb6ee6975 in QApplication::notify (this=0xbfa626e8, receiver=0x85984b0, 
    e=0xbfa62204) at kernel/qapplication.cpp:2478
#50 0xb7625ff2 in KApplication::notify (this=0xbfa626e8, receiver=0x85984b0, 
    event=0xbfa62204)
    at /build/buildd/kdelibs-3.5.7.dfsg.1/./kdecore/kapplication.cpp:550
#51 0xb6e7573d in QApplication::sendSpontaneousEvent (receiver=0x85984b0, 
    event=0xbfa62204) at kernel/qapplication.h:523
#52 0xb6e74445 in QETWidget::translateMouseEvent (this=0x85984b0, 
    event=0xbfa62548) at kernel/qapplication_x11.cpp:4305
#53 0xb6e72858 in QApplication::x11ProcessEvent (this=0xbfa626e8, 
    event=0xbfa62548) at kernel/qapplication_x11.cpp:3478
#54 0xb6e8967c in QEventLoop::processEvents (this=0x80ab0a8, flags=4)
    at kernel/qeventloop_x11.cpp:192
#55 0xb6eff6e4 in QEventLoop::enterLoop (this=0x80ab0a8)
    at kernel/qeventloop.cpp:198
#56 0xb6eff3e2 in QEventLoop::exec (this=0x80ab0a8)
    at kernel/qeventloop.cpp:145
#57 0xb6ee5f13 in QApplication::exec (this=0xbfa626e8)
    at kernel/qapplication.cpp:2758
#58 0x08059989 in main (argc=1326492, argv=0xbfa628f4)
    at /build/buildd/kdepim-3.5.7/./kontact/src/main.cpp:163
#59 0xb76c3050 in __libc_start_main () from /lib/libc.so.6
#60 0x08059111 in _start ()