Version:           Unbekannt (using 4.3.4 (KDE 4.3.4), Debian packages)
Compiler:          cc
OS:                Linux (i686) release 2.6.32-trunk-686

Hello,
since 2 or 3 days, my kontact doesn't start anymore. A execution on the shell reports:

<start>
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Calling appendChild() on a null node does nothing.
Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
QObject::connect: Cannot queue arguments of type 'KParts::WindowArgs'
(Make sure 'KParts::WindowArgs' is registered using qRegisterMetaType().)
<unknown program name>(31201)/: Communication problem with  "kontact" , it probably crashed.
Error message was:  "org.freedesktop.DBus.Error.NoReply" : " "Message did not receive a reply (timeout by message bus)" "
<end>

Other kde-programms are working without probelms – even kmail works (so that I can still read my emails), but kontact doesn't. Sometimes at kde-startup it reports that there is another kontact-session already open, but no matter what I select, kontact does not start.
I share my home between 2 computers, but use it exclusive only on 1 of them on the same time, so that shouldn't cause the problem.