Version:           1.10.0 (using 4.1.00 (KDE 4.1.0), Debian packages)
Compiler:          cc
OS:                Linux (i686) release 2.6.25-2-486

Testcase (all may not be useful) :

- Enable the spam filtering without installing any spam detection tool (eg. spamassassin).

- Try to disable it using the Tools/spam filtering menu. After unchecking the two boxes and finally click on finish, kmail crashes.

/bin/sh: crm: command not found
/bin/sh: bsfilter: command not found
/bin/sh: bogofilter: command not found
/bin/sh: spamc: command not found     
/bin/sh: spamassassin: command not found
/bin/sh: spamassassin: command not found
/bin/sh: /home/krop/.annoyance-filter/annoyance-filter: No such file or directory
/bin/sh: sb_filter.py: command not found                                         
==20732==                                                                        
==20732== Invalid read of size 4                                                 
==20732==    at 0x424E7EF: (within /usr/lib/libkmailprivate.so.4.1.0)            
==20732==    by 0x44737B7: (within /usr/lib/libkmailprivate.so.4.1.0)            
==20732==    by 0x55FAD15: QDialog::qt_metacall(QMetaObject::Call, int, void**) (moc_qdialog.cpp:87)
==20732==    by 0x49E8589: KDialog::qt_metacall(QMetaObject::Call, int, void**) (kdialog.moc:142)   
==20732==    by 0x4AB53D9: KPageDialog::qt_metacall(QMetaObject::Call, int, void**) (kpagedialog.moc:63)
==20732==    by 0x49D1B89: KAssistantDialog::qt_metacall(QMetaObject::Call, int, void**) (kassistantdialog.moc:63)
==20732==    by 0x4477A39: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x4F8E0BF: QMetaObject::activate(QObject*, int, int, void**) (qobject.cpp:3010)                   
==20732==    by 0x4F8EE41: QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (qobject.cpp:3080)    
==20732==    by 0x49E5576: KDialog::user1Clicked() (kdialog.moc:229)                                              
==20732==    by 0x49E82AC: KDialog::slotButtonClicked(int) (kdialog.cpp:860)                                      
==20732==    by 0x49E85F3: KDialog::qt_metacall(QMetaObject::Call, int, void**) (kdialog.moc:181)                 
==20732==  Address 0x8cfca6c is 4 bytes after a block of size 32 alloc'd                                          
==20732==    at 0x4022E8C: realloc (vg_replace_malloc.c:429)                                                      
==20732==    by 0x4E84AD3: qRealloc(void*, unsigned) (qmalloc.cpp:67)                                             
==20732==    by 0x4EAD984: QListData::realloc(int) (qlistdata.cpp:113)                                            
==20732==    by 0x4EADBF2: QListData::append() (qlistdata.cpp:133)                                                
==20732==    by 0x422810A: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x4250FD1: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x424E300: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x43345C8: KMKernel::init() (in /usr/lib/libkmailprivate.so.4.1.0)                                
==20732==    by 0x804A659: main (main.cpp:128)                                                                    
==20732==                                                                                                         
==20732== Invalid read of size 4                                                                                  
==20732==    at 0x424E7F1: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x44737B7: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x55FAD15: QDialog::qt_metacall(QMetaObject::Call, int, void**) (moc_qdialog.cpp:87)              
==20732==    by 0x49E8589: KDialog::qt_metacall(QMetaObject::Call, int, void**) (kdialog.moc:142)                 
==20732==    by 0x4AB53D9: KPageDialog::qt_metacall(QMetaObject::Call, int, void**) (kpagedialog.moc:63)          
==20732==    by 0x49D1B89: KAssistantDialog::qt_metacall(QMetaObject::Call, int, void**) (kassistantdialog.moc:63)
==20732==    by 0x4477A39: (within /usr/lib/libkmailprivate.so.4.1.0)                                             
==20732==    by 0x4F8E0BF: QMetaObject::activate(QObject*, int, int, void**) (qobject.cpp:3010)                   
==20732==    by 0x4F8EE41: QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (qobject.cpp:3080)    
==20732==    by 0x49E5576: KDialog::user1Clicked() (kdialog.moc:229)                                              
==20732==    by 0x49E82AC: KDialog::slotButtonClicked(int) (kdialog.cpp:860)                                      
==20732==    by 0x49E85F3: KDialog::qt_metacall(QMetaObject::Call, int, void**) (kdialog.moc:181)                 
==20732==  Address 0x85 is not stack'd, malloc'd or (recently) free'd                                             
*** KMail got signal 11 (Crashing)            


and finally the bt. (even with kdelibs/pimlibs/pim debug packages, some useful things are missing in my bt)

Application: KMail (kmail), signal SIGSEGV
[Thread debugging using libthread_db enabled]
[New Thread 0xb41e7700 (LWP 20809)]
[New Thread 0xb1163b90 (LWP 20814)]
[KCrash handler]
#6  0xb7a187f1 in ?? () from /usr/lib/libkmailprivate.so.4
#7  0xb7c3d7b8 in ?? () from /usr/lib/libkmailprivate.so.4
#8  0xb6be0d16 in QDialog::qt_metacall () from /usr/lib/libQtGui.so.4
#9  0xb74a958a in KDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=32, _a=0xbfc8a278)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kdialog.moc:142
#10 0xb75763da in KPageDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=32, _a=0xbfc8a278)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kpagedialog.moc:63
#11 0xb7492b8a in KAssistantDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=32, _a=0xbfc8a278)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kassistantdialog.moc:63
#12 0xb7c41a3a in ?? () from /usr/lib/libkmailprivate.so.4
#13 0xb70900c0 in QMetaObject::activate (sender=0xbfc8b454, 
    from_signal_index=41, to_signal_index=41, argv=0x0)
    at kernel/qobject.cpp:3010
#14 0xb7090e42 in QMetaObject::activate (sender=0xbfc8b454, m=0xb76cba44, 
    local_signal_index=6, argv=0x0) at kernel/qobject.cpp:3080
#15 0xb74a6577 in KDialog::user1Clicked (this=0xbfc8b454)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kdialog.moc:229
#16 0xb74a92ad in KDialog::slotButtonClicked (this=0xbfc8b454, button=4096)
    at /tmp/buildd/kde4libs-4.1.0/kdeui/dialogs/kdialog.cpp:860
#17 0xb74a95f4 in KDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=33, _a=0xbfc8a49c)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kdialog.moc:181
#18 0xb75763da in KPageDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=68, _a=0xbfc8a49c)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kpagedialog.moc:63
#19 0xb7492b8a in KAssistantDialog::qt_metacall (this=0xbfc8b454, 
    _c=QMetaObject::InvokeMetaMethod, _id=68, _a=0xbfc8a49c)
    at /tmp/buildd/kde4libs-4.1.0/obj-i486-linux-gnu/kdeui/kassistantdialog.moc:63
#20 0xb7c41a3a in ?? () from /usr/lib/libkmailprivate.so.4
#21 0xb70900c0 in QMetaObject::activate (sender=0x8a823e0, 
    from_signal_index=4, to_signal_index=4, argv=0xbfc8a49c)
    at kernel/qobject.cpp:3010
#22 0xb7090e42 in QMetaObject::activate (sender=0x8a823e0, m=0xb715ca58, 
    local_signal_index=0, argv=0xbfc8a49c) at kernel/qobject.cpp:3080
#23 0xb7093f53 in QSignalMapper::mapped (this=0x8a823e0, _t1=4096)
    at .moc/release-shared/moc_qsignalmapper.cpp:93
#24 0xb70947dd in QSignalMapper::map (this=0x8a823e0, sender=0x8a66b60)
    at kernel/qsignalmapper.cpp:277
#25 0xb70949ce in QSignalMapper::map (this=0x8a823e0)
    at kernel/qsignalmapper.cpp:268
#26 0xb709529b in QSignalMapper::qt_metacall (this=0x8a823e0, 
    _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0xbfc8a61c)
    at .moc/release-shared/moc_qsignalmapper.cpp:80
#27 0xb70900c0 in QMetaObject::activate (sender=0x8a66b60, 
    from_signal_index=29, to_signal_index=30, argv=0xbfc8a61c)
    at kernel/qobject.cpp:3010
#28 0xb70904c0 in QMetaObject::activate (sender=0x8a66b60, m=0xb6f28c44, 
    from_local_signal_index=2, to_local_signal_index=3, argv=0xbfc8a61c)
    at kernel/qobject.cpp:3100
#29 0xb6d5fe21 in QAbstractButton::clicked () from /usr/lib/libQtGui.so.4
#30 0xb6ab57d9 in ?? () from /usr/lib/libQtGui.so.4
#31 0xb6ab7344 in ?? () from /usr/lib/libQtGui.so.4
#32 0xb6ab75d6 in QAbstractButton::mouseReleaseEvent ()
   from /usr/lib/libQtGui.so.4
#33 0xb67d64f2 in QWidget::event () from /usr/lib/libQtGui.so.4
#34 0xb6ab567e in QAbstractButton::event () from /usr/lib/libQtGui.so.4
#35 0xb6b5b5c0 in QPushButton::event () from /usr/lib/libQtGui.so.4
#36 0xb677e66c in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#37 0xb6786df1 in QApplication::notify () from /usr/lib/libQtGui.so.4
#38 0xb754568d in KApplication::notify (this=0xbfc8c5b8, receiver=0x8a66b60, 
    event=0xbfc8acbc)
    at /tmp/buildd/kde4libs-4.1.0/kdeui/kernel/kapplication.cpp:311
#39 0xb707b571 in QCoreApplication::notifyInternal (this=0xbfc8c5b8, 
    receiver=0x8a66b60, event=0xbfc8acbc) at kernel/qcoreapplication.cpp:587
#40 0xb678607e in QApplicationPrivate::sendMouseEvent ()
   from /usr/lib/libQtGui.so.4
#41 0xb67ef5fd in ?? () from /usr/lib/libQtGui.so.4
#42 0xb67ee3cf in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#43 0xb6817d14 in ?? () from /usr/lib/libQtGui.so.4
#44 0xb4b482e1 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#45 0xb4b4b973 in ?? () from /usr/lib/libglib-2.0.so.0
#46 0x08355e90 in ?? ()
#47 0x00000000 in ?? ()
#0  0xb7f70430 in __kernel_vsyscall ()