bad h264 playsback

[AveryAndrews]

For about a month, I've been experiencing a wide range of peculiar artifacts playing most but not all h264-encoded videos, such as for example http://vimeo.com/18305022. The artifacts are parts of the picture with blocks, bars, bad colors, etc, periodically clearing up and reappearing, as if something was going wrong with decompression of the effects of movements.

This appears with pretty well all players and codecs that I've tried (except for coreavi, due it's not having a free demo anymore), but I'm now having it on a system with no video stuff other than vlc installed, so, am hoping that somebody here might have some insight. I also get it on multiple computers with various kinds of mobos and gfx cards.