same here!
$ kontact
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
unnamed app(22506): 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)" "
$ kontact --version
Qt: 4.8.6
KDE Development Platform: 4.13.1
Kontact: 4.12.2
$ inxi -r
Repos: Active apt sources in file: /etc/apt/sources.list.d/debian.list
deb http://ftp.it.debian.org/debian/ unstable main contrib non-free
deb http://ftp.it.debian.org/debian/ experimental main
Active apt sources in file: /etc/apt/sources.list.d/dropbox.list
deb http://linux.dropbox.com/debian sid main
Active apt sources in file: /etc/apt/sources.list.d/lxqt.list
deb http://packages.siduction.org/lxqt next main
Active apt sources in file: /etc/apt/sources.list.d/misc.list
deb http://ftp.spline.de/pub/siduction/user unstable main
deb http://ftp.spline.de/pub/siduction/kdenext unstable main
deb http://packages.siduction.org/kdenext kdepim-ng main
Active apt sources in file: /etc/apt/sources.list.d/pipelight.list
deb http://repos.fds-team.de/stable/debian/ sid main
Active apt sources in file: /etc/apt/sources.list.d/siduction.list
deb http://ftp.spline.de/pub/siduction/base unstable main
deb http://ftp.spline.de/pub/siduction/extra unstable main
deb http://ftp.spline.de/pub/siduction/fixes unstable main