I get the same blue screen problem with my Ti4200 and 4496 drivers. Something is wrong with Xv. I have been less than impressed with Nvidia drivers for a while; it would help if there was an actual ChangeLog or buglist.
Sometimes with video playback and hardware acceleration, my desktop will lock up. It seems with every release, new stuff is added but old stuff is broken, and the speed drops. 5336 runs one of my benchmark apps at 23 M tris/sec; 4496 runs it at 29 mil tps; with a driver in the 3xxx series, it was 40 mil.