Can't Encode H.264 (Adobe CS5) Successfully

When I try and use graphics card acceleration in Premiere Pro CS5 the file ends up corrupted and jittery. I have a mac pro 6-core 3.33, with 16 gigs of ram, Quadro 4000, and I’ve tried running both of the most recent driver, …21 and …31.

Can someone tell me what I should do?