AFAIK you're quite correct in your assesment that PB is behind your woes.
Unfortunately, it is unknown when they will "get around" to fix the problem. They've gotten complaints from ATI users for quite some time, and now nvidia users are experiencing the same. (Nvidia can reproduce the problem and openly admits that it's not just an ATI problem) But there has not been much help forthcoming from the people behind PB, so no-one really knows what is happening to resolve the problem.
There has been some talk about the newest beta drivers from ATI fixing the problem (they're on ATI's download page due to ram mapping fault with older drivers), but I don't know if it works for everyone or not.
Hopefully they'll help you out, otherwise you'll have to roll back to a previous driver release, though you might encounter stuttering with those.