kontact kmail crashes on closing

Kontact/Kmail crashes when closing with the upper right close button, after a few action on an IMAP server. Using a POP account or closing from the file menu may not crash.

System : Up to date Kubuntu Intrepid with Kmail 1.10.1, Kontact 1.3, KDE 4.1.3
uname -a
Linux tpad-z60m 2.6.27-9-generic #1 SMP Thu Nov 20 21:57:00 UTC 2008 i686 GNU/Linux

When run under gdb kontact, an assertion is triggered in qhash.h:
...
kontact(26592)/kmail KMReaderWin::parseMsg: Finished parsing and displaying of message.
QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::setWorldTransform: Painter not active
kontact(26592)/kmail KMailPart::guiActivateEvent:
kontact(26592)/kmail KMailPart::~KMailPart: Closing last KMMainWin: stopping mail check
kontact(26592)/kmail KMail::PopAccount::slotAbortRequested:
ASSERT: "item_exists()" in file /usr/include/qt4/QtCore/qhash.h, line 1006
*** KMail got signal 6 (Crashing)
KCrash: Application 'kontact' crashing...
sock_file=/home/naso/.kde/socket-tpad-z60m/kdeinit4__0

Crash log gives:

Application : Kontact (kontact), signal SIGABRT
[Thread debugging using libthread_db enabled]
[New Thread 0xb4de36c0 (LWP 32105)]
[New Thread 0xb0db1b90 (LWP 32119)]
[KCrash handler]
#6 0xb80be430 in __kernel_vsyscall ()
#7 0xb6c46880 in raise () from /lib/tls/i686/cmov/libc.so.6
#8 0xb6c48248 in abort () from /lib/tls/i686/cmov/libc.so.6
#9 0xb77ba795 in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb77ba872 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb77ba915 in qt_assert () from /usr/lib/libQtCore.so.4
#12 0xb174452d in ~KMAcctImap (this=0xa2c4770)
    at /usr/include/qt4/QtCore/qhash.h:1006
#13 0xb16c052e in ~AccountManager (this=0xa276a40)
    at /usr/include/qt4/QtCore/qalgorithms.h:346
#14 0xb17b011e in KMKernel::cleanup (this=0xa225270)
    at /build/buildd/kdepim-4.1.2/kmail/kmkernel.cpp:1683
#15 0xb1c4168b in ~KMailPart (this=0xa1f7c20)
    at /build/buildd/kdepim-4.1.2/kmail/kmail_part.cpp:138
#16 0xb806d292 in ~MainWindow (this=0x9dd0e08)
    at /build/buildd/kdepim-4.1.2/kontact/src/mainwindow.cpp:252
#17 0xb78c0dec in qDeleteInEventHandler () from /usr/lib/libQtCore.so.4
#18 0xb78c27a3 in QObject::event () from /usr/lib/libQtCore.so.4
#19 0xb6ffb044 in QWidget::event () from /usr/lib/libQtGui.so.4
#20 0xb734f497 in QMainWindow::event () from /usr/lib/libQtGui.so.4
#21 0xb7e53958 in KMainWindow::event (this=0x9dd0e08, ev=0xa8703c0)
    at /build/buildd/kde4libs-4.1.3/kdeui/widgets/kmainwindow.cpp:1073
etc.

The two files are included.