Version:           1.8.50 (using KDE 3.4.89 (>= 20050508), compiled sources)
Compiler:          gcc version 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
OS:                Linux (i686) release 2.6.9-1.667

What I did :
I select a folder. Then I get this message that the .index file is corrupted. But I was too quick for this message as I needed another folder. So before I clicked OK on the message, I already clicked on this other folder. Now, when I click OK on the message, kmail crashes.

Using host libthread_db library "/lib/tls/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -184993280 (LWP 4997)]
[KCrash handler]
#4  0x007577a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#5  0x00797955 in raise () from /lib/tls/libc.so.6
#6  0x00799319 in abort () from /lib/tls/libc.so.6
#7  0x00790f41 in __assert_fail () from /lib/tls/libc.so.6
#8  0xf6dcc4b9 in KMFolderMbox::createIndexFromContents (this=0x8797208)
    at kmfoldermbox.cpp:562
#9  0xf6dc9de3 in KMFolderMbox::open (this=0x8797208) at kmfoldermbox.cpp:170
#10 0xf6d36697 in KMFolder::open (this=0x8797100) at kmfolder.cpp:433
#11 0xf6cf43d8 in KMHeaders::setFolder (this=0x87ce9b0, aFolder=0x8797100, 
    forceJumpToUnread=false) at kmheaders.cpp:708
#12 0xf6e833b9 in KMMainWidget::folderSelected (this=0x87c8128, 
    aFolder=0x8797100, forceJumpToUnread=false) at kmmainwidget.cpp:1766
#13 0xf6e79f63 in KMMainWidget::qt_invoke (this=0x87c8128, _id=50, 
    _o=0xfef931e0) at kmmainwidget.moc:486
#14 0xf52b3bb8 in QObject::activate_signal ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#15 0xf6cdea4c in KMFolderTree::folderSelected (this=0x8861ed0, t0=0x8797100)
    at kmfoldertree.moc:384
#16 0xf6cda398 in KMFolderTree::doFolderSelected (this=0x8861ed0, 
    qlvi=0x88a4600) at kmfoldertree.cpp:917
#17 0xf6cdb245 in KMFolderTree::contentsMouseReleaseEvent (this=0x8861ed0, 
    me=0xfef932d0) at kmfoldertree.cpp:1075
#18 0xf53a98d5 in QScrollView::viewportMouseReleaseEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#19 0xf53a9294 in QScrollView::eventFilter ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#20 0xf537dfbd in QListView::eventFilter ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#21 0xf6cdd3eb in KMFolderTree::eventFilter (this=0x8861ed0, o=0x8862860, 
    e=0xfef93820) at kmfoldertree.cpp:1633
#22 0xf52b1a1c in QObject::activate_filters ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#23 0xf52b196a in QObject::event ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#24 0xf52e2aa6 in QWidget::event ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#25 0xf5261e2d in QApplication::internalNotify ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#26 0xf5261594 in QApplication::notify ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#27 0xf578ed44 in KApplication::notify (this=0xfef94ef0, receiver=0x8862860, 
    event=0xfef93820) at kapplication.cpp:549
#28 0xf52033cb in QETWidget::translateMouseEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#29 0xf52012a9 in QApplication::x11ProcessEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#30 0xf5215680 in QEventLoop::processEvents ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#31 0xf52718f3 in QEventLoop::enterLoop ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#32 0xf5262080 in QApplication::enter_loop ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#33 0xf540dc54 in QDialog::exec ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#34 0xf5ae3850 in KMessageBox::createKMessageBox (dialog=0x8bc13e0, 
    icon=<incomplete type>, text=@0xfef94010, strlist=@0xfef93f90, 
    ask=@0xfef93ed0, checkboxReturn=0xfef93ecf, options=2, 
    details=@0xf56b08bc, notifyType=Information) at kmessagebox.cpp:311
#35 0xf5ae2fbd in KMessageBox::createKMessageBox (dialog=0x8bc13e0, 
    icon=Information, text=@0xfef94010, strlist=@0xfef93f90, ask=@0xfef93ed0, 
    checkboxReturn=0xfef93ecf, options=2, details=@0xf56b08bc)
    at kmessagebox.cpp:147
#36 0xf5ae5a19 in KMessageBox::informationListWId (parent_id=0, 
    text=@0xfef94010, strlist=@0xfef93f90, caption=@0xfef94030, 
    dontShowAgainName=@0xfef94020, options=2) at kmessagebox.cpp:929
#37 0xf5ae5818 in KMessageBox::informationList (parent=0x0, text=@0xfef94010, 
    strlist=@0xfef93f90, caption=@0xfef94030, dontShowAgainName=@0xfef94020, 
    options=2) at kmessagebox.cpp:903
#38 0xf5ae5763 in KMessageBox::information (parent=0x0, text=@0xfef94010, 
    caption=@0xfef94030, dontShowAgainName=@0xfef94020, options=2)
    at kmessagebox.cpp:888
#39 0xf6dc9bf4 in KMFolderMbox::open (this=0x8797f58) at kmfoldermbox.cpp:151
#40 0xf6d36697 in KMFolder::open (this=0x8797e50) at kmfolder.cpp:433
#41 0xf6cf43d8 in KMHeaders::setFolder (this=0x87ce9b0, aFolder=0x8797e50, 
    forceJumpToUnread=false) at kmheaders.cpp:708
#42 0xf6e833b9 in KMMainWidget::folderSelected (this=0x87c8128, 
    aFolder=0x8797e50, forceJumpToUnread=false) at kmmainwidget.cpp:1766
#43 0xf6e79f63 in KMMainWidget::qt_invoke (this=0x87c8128, _id=50, 
    _o=0xfef94280) at kmmainwidget.moc:486
#44 0xf52b3bb8 in QObject::activate_signal ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#45 0xf6cdea4c in KMFolderTree::folderSelected (this=0x8861ed0, t0=0x8797e50)
    at kmfoldertree.moc:384
#46 0xf6cda398 in KMFolderTree::doFolderSelected (this=0x8861ed0, 
    qlvi=0x88a48f8) at kmfoldertree.cpp:917
#47 0xf6cdb245 in KMFolderTree::contentsMouseReleaseEvent (this=0x8861ed0, 
    me=0xfef94370) at kmfoldertree.cpp:1075
#48 0xf53a98d5 in QScrollView::viewportMouseReleaseEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#49 0xf53a9294 in QScrollView::eventFilter ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#50 0xf537dfbd in QListView::eventFilter ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#51 0xf6cdd3eb in KMFolderTree::eventFilter (this=0x8861ed0, o=0x8862860, 
    e=0xfef948c0) at kmfoldertree.cpp:1633
#52 0xf52b1a1c in QObject::activate_filters ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#53 0xf52b196a in QObject::event ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#54 0xf52e2aa6 in QWidget::event ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#55 0xf5261e2d in QApplication::internalNotify ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#56 0xf5261594 in QApplication::notify ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#57 0xf578ed44 in KApplication::notify (this=0xfef94ef0, receiver=0x8862860, 
    event=0xfef948c0) at kapplication.cpp:549
#58 0xf52033cb in QETWidget::translateMouseEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#59 0xf52012a9 in QApplication::x11ProcessEvent ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#60 0xf5215680 in QEventLoop::processEvents ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#61 0xf52718f3 in QEventLoop::enterLoop ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#62 0xf52717b8 in QEventLoop::exec ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#63 0xf526202c in QApplication::exec ()
   from /hda8/opt/qt-copy.20050207/lib/libqt-mt.so.3
#64 0x0804aa2f in main (argc=7, argv=0xfef950a4) at main.cpp:110