At the end of the last d-u (kernel 3.6-2) I got an error about virtualbox.
/var/lib/dkms/virtualbox-guest/4.1.18/build/make.log tells me:
/var/lib/dkms/virtualbox-guest/4.1.18/build/vboxvideo/vboxvideo_drm.c:106:5: error: unknown field ‘reclaim_buffers’ specified in initializer
/var/lib/dkms/virtualbox-guest/4.1.18/build/vboxvideo/vboxvideo_drm.c:106:5: warning: initialization from incompatible pointer type [enabled by default]
/var/lib/dkms/virtualbox-guest/4.1.18/build/vboxvideo/vboxvideo_drm.c:106:5: warning: (near initialization for ‘driver.firstopen’) [enabled by default]
make[2]: *** [/var/lib/dkms/virtualbox-guest/4.1.18/build/vboxvideo/vboxvideo_drm.o] Fehler 1
make[1]: *** [/var/lib/dkms/virtualbox-guest/4.1.18/build/vboxvideo] Fehler 2
make: *** [_module_/var/lib/dkms/virtualbox-guest/4.1.18/build] Fehler 2