Hello, I have found some elements about this issue. I had somewhere an export vblank_mode=1. When vblank_mode=2 (default value that means synchronized to the vertical refresh), there are not still video corruption when I am logged, but under gdm3, they exists still. vblank_mode=2 gets best videos movies playing results (flashplayer) but poor gtk performance (with getkperf). Regards. -- Alain Rpnpif