I'm really not sure what is going on here but I seem to have a strange problem. When I play certain AVI files (DivX or XviD, I'm not sure which), during playback the upper-right corner will get blocky for a second and then go back to normal. The blockyness is strange because it seems to start in the upper-right and move diagonally towards the center. Here is a drawing of what happens: (the red area is the blocky area) I've re-installed Windows XP and have ONLY installed the official XviD codec (which decodes DivX as well). I also have an nVidia 8800 GTX with the latest drivers but I don't know if that matters. The problem is also strange because it doesn't happen on all files... it seems to be completely random.