Well, I don't think it's a memory problem since I have 1 GB of ram in my PB. Unless maybe if I have bad ram or something, but I haven't noticed anything else really weird.
senne, you're problem sounds really weird! You should get a screenshot movie with Snapz Pro X (if you have it) and post it or something!
Interesting that the Carbon Sound Manager update seems to have caused the problem for Tormente, fixed the problem for aaike and done nothing for me!
At least we know that iMac's, PowerMac's & PowerBook's all have this problem in one form or another.
Nobody ever had this problem in 10.1 though, right?