ahh, same problem i got mate, reinstalled windows, update evrything, correctly installed drivers for gfx card n motherbaord all that shiz then everything downloaded just wont play and pc goes slower than my grans car when i try to watch, I just log out n log in again sorts the slowness out, but still no vid. the only vids i can watch are internet hosted and downloaded from bit-torent but not for long, getting new motherboard, another gb of ram and new hdd so, after yet another windows install fingers crossed its sorted Tim.