after returning from hibernation, the session is broken

[Katsudon]

Kubuntu Intrepid Beta with all upgrades.

I have been using hibernation very often, but so far the following bug occured only once:
after coming back from hibernation only part of the screen came back (a rectangular part in the upper left, corner, maybe 50% of the screen area), the rest was black.

I could move the cursor but clicking and keyboard did not help.

After logging to the text console (Alt-F1) I found two zombie processes, both related to "ksmserver".
Killing the two zombie processes resulted in new login screen.

[Katsudon (katsudon)]

The problem did not come back in the last weeks, maybe some upgrades solved it.