i found the root of the problem:
after removing the package gstreamer0.10-plugins-bad, i was able to view the properties window in nautilus as it should be.
the totem player now complains about a missing codec and suggests to install gstreamer0.10-plugins-bad but there's no memory leakage anymore.
thus the problem seems to be in the gstreamer0.10-plugins-bad package
i found the root of the problem:
after removing the package gstreamer0. 10-plugins- bad, i was able to view the properties window in nautilus as it should be.
the totem player now complains about a missing codec and suggests to install gstreamer0. 10-plugins- bad but there's no memory leakage anymore.
thus the problem seems to be in the gstreamer0. 10-plugins- bad package