Version:           1.9.4 (using KDE KDE 3.5.4)
Installed from:    SuSE RPMs
OS:                Linux

I removed a very full, lots of subfolders, with lots of mails in them, cached imap account. kmail was still in the phase of removing the cached imap account data. I started creating a new imap account with same information, name, server, ... the only difference was that it not was a cached imap account.

the crash handler came up with the following backtrace:
Using host libthread_db library "/lib/tls/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 1113763904 (LWP 10785)]
[New Thread 1126394800 (LWP 10795)]
[Thread debugging using libthread_db enabled]
[New Thread 1113763904 (LWP 10785)]
[New Thread 1126394800 (LWP 10795)]
[Thread debugging using libthread_db enabled]
[New Thread 1113763904 (LWP 10785)]
[New Thread 1126394800 (LWP 10795)]
[New Thread 1124293552 (LWP 10794)]
[New Thread 1122192304 (LWP 10793)]
[New Thread 1120091056 (LWP 10792)]
[KCrash handler]
#9  0x40d39a7d in QString::QString () from /usr/lib/qt3/lib/libqt-mt.so.3
#10 0x403f7cdf in KMail::CachedImapJob::slotGetNextMessage ()
   from /opt/kde3/lib/libkmailprivate.so
#11 0x403f917e in KMail::CachedImapJob::qt_invoke ()
   from /opt/kde3/lib/libkmailprivate.so
#12 0x40a4ec4e in QObject::activate_signal ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#13 0x41b91182 in KIO::Job::result () from /opt/kde3/lib/libkio.so.4
#14 0x41bf121c in KIO::Job::emitResult () from /opt/kde3/lib/libkio.so.4
#15 0x41bf8cfc in KIO::SimpleJob::slotFinished ()
   from /opt/kde3/lib/libkio.so.4
#16 0x41bf94aa in KIO::TransferJob::slotFinished ()
   from /opt/kde3/lib/libkio.so.4
#17 0x41be51b7 in KIO::TransferJob::qt_invoke () from /opt/kde3/lib/libkio.so.4
#18 0x40a4ec4e in QObject::activate_signal ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#19 0x40a4f3f6 in QObject::activate_signal ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#20 0x41b9694c in KIO::SlaveInterface::finished ()
   from /opt/kde3/lib/libkio.so.4
#21 0x41bcb408 in KIO::SlaveInterface::dispatch ()
   from /opt/kde3/lib/libkio.so.4
#22 0x41ba5e03 in KIO::SlaveInterface::dispatch ()
   from /opt/kde3/lib/libkio.so.4
#23 0x41ba710b in KIO::Slave::gotInput () from /opt/kde3/lib/libkio.so.4
#24 0x41bce86a in KIO::Slave::qt_invoke () from /opt/kde3/lib/libkio.so.4
#25 0x40a4ec4e in QObject::activate_signal ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#26 0x40a4f27d in QObject::activate_signal ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#27 0x40da9990 in QSocketNotifier::activated ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#28 0x40a6e610 in QSocketNotifier::event () from /usr/lib/qt3/lib/libqt-mt.so.3
#29 0x409eb62f in QApplication::internalNotify ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#30 0x409ed213 in QApplication::notify () from /usr/lib/qt3/lib/libqt-mt.so.3
#31 0x406fb0f1 in KApplication::notify () from /opt/kde3/lib/libkdecore.so.4
#32 0x409df636 in QEventLoop::activateSocketNotifiers ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#33 0x40998145 in QEventLoop::processEvents ()
   from /usr/lib/qt3/lib/libqt-mt.so.3
#34 0x40a033f1 in QEventLoop::enterLoop () from /usr/lib/qt3/lib/libqt-mt.so.3
#35 0x40a03236 in QEventLoop::exec () from /usr/lib/qt3/lib/libqt-mt.so.3
#36 0x409ed0df in QApplication::exec () from /usr/lib/qt3/lib/libqt-mt.so.3
#37 0x0804a6a6 in main ()