Version:            (using Devel)
Installed from:    Compiled sources
Compiler:          gcc 4.3.0 
OS:                Linux

I had 4 tabs opened, I closed one and almost immediatly I quitted Konqueror. I would suspect Konqueror was cleaning the cache of the closed tab but not fast enough. I am not a KDE developer so take my hunch with a grain of salt.

Here is the backtrace:

Application: Konqueror (konqueror), signal SIGABRT
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 0xb60f88e0 (LWP 9900)]
[KCrash handler]
#6  0xb7fd3410 in __kernel_vsyscall ()
#7  0xb6482400 in raise () from /lib/libc.so.6
#8  0xb6483d38 in abort () from /lib/libc.so.6
#9  0xb647b49e in __assert_fail () from /lib/libc.so.6
#10 0xb42d5029 in KHTMLGlobal::finalCheck ()
    at /home/kde-devel/kde/src/KDE/kdelibs/khtml/khtml_global.cpp:246
#11 0xb478e365 in ~KHTMLFactory (this=0x82d6b28)
    at /home/kde-devel/kde/src/KDE/kdelibs/khtml/khtml_factory.cpp:35
#12 0xb72015bf in QObjectCleanupHandler::clear (this=0x82d67b0)
    at kernel/qobjectcleanuphandler.cpp:142
#13 0xb7201630 in ~QObjectCleanupHandler (this=0x82d67b0)
    at kernel/qobjectcleanuphandler.cpp:88
#14 0xb7c0f810 in destroy ()
    at /home/kde-devel/kde/src/KDE/kdelibs/kdecore/util/kpluginfactory.cpp:29
#15 0xb7aefaf1 in ~KCleanUpGlobalStatic (this=0xb7c4d814)
    at /home/kde-devel/kde/src/KDE/kdelibs/kdecore/kernel/kglobal.h:65
#16 0xb6485329 in exit () from /lib/libc.so.6
#17 0xb646e39e in __libc_start_main () from /lib/libc.so.6
#18 0x08048731 in _start ()
#0  0xb7fd3410 in __kernel_vsyscall ()