I’ve been having intermittently blocky h264 playback for some but not all files, with a pretty wide range of players and codec packs (both k-light and cccp for example), under both XP and Win 7, on two different computers, whose only thing in common are gigabite boards and ati cards (different generations). The problem seems to have started about a month ago, no issues before then. The blockiness affects only part of the screen, sometimes a lot, sometimes a little, and periodically clears up and then builds up again (as iff the 'update' aspect of the decompression was messed up, but the keyframes were OK). None of the usual things that people recommend for h264 problems(disabling DXVA hardware acceleration, installing DIVX h264, etc etc) seem to make any difference whatsoever, which makes me think I must be overlooking something very basic. The problems arise with both 'virgin' XP and Win7 installs with latest drivers, directx, k-lite or cccp.