After Kernel header update in precise no Unity sidebar nor task bar nor dash.

Hello there!

I'm having trouble with my desktop under Ubuntu Precise on i386. After updating the kernel headers to 3.2.0-36.57 via the regular update procedure I suddenly have neither the Dash nor the task bar nor the side bar. I do have the Desktop though. The only error message produced comes from the hplip tool which says that it coulden't detect a task bar. In history.log, kern.log, term.log and Xorg.0.log there were no clues to what went wrong - as far as I could tell. Has anyone had the same problem and managed to solve it? Or does anyone have a clue where to search for the problem? Google did not turn out to be the right place.
I would be very glad if anyone could help me on this. Thanks in advance!