I read something similar on the MythTV mailinglist.
From http://www.gossamer-threads.com/lists/mythtv/users/366684: In the end I believe it was accidental code bugs when he was porting the automatic letterboxing patch over to work with VDPAU that caused him to end up with his OSD ghosted over every image displayed via VDPAU.
Are you sure that this is the right thread? Someone thinks vdpau has destroyed his video card.
Gerald