From time to time when I switch in kontact from one view to the contacts
view, kontact crashes. Now I looked into .xsession-err

*** Error in `kontact': malloc(): memory corruption (fast):
0x0000000002291eeb ***
[TDE NM Backend ERROR]
[/opt/software_x64/KDE/TDE/tdelibs/tdecore/tdehw/networkbackends/network-manager/network-manager.cpp:1823]
Attempting to access the network-manager VPN service returned:
org.freedesktop.DBus.Error.ServiceUnknown: The name
org.freedesktop.NetworkManager.VPN.Plugin was not provided by any .service
files
WeaverThreadLogger: thread (ID: 2) suspended.
WeaverThreadLogger: thread (ID: 4) suspended.
WeaverThreadLogger: thread (ID: 3) suspended.
WeaverThreadLogger: thread (ID: 1) suspended.
*** KMail got signal 6 (Crashing)

How can I track this down? Should I turn on debugging for all that ... and
what partiularly

thanks
regards