HELP!!!!!.....cannot play any music or video files........HELP!!!

hey guys

i have some troubles to play all kind of media files now. the problem comes out a few days ago and i have no idea what may be the reason. i am very sure i didn't install anything to my computer and there is no notifications to tell me anything that is damaged etc. and i just reinstall the entire computer once today but the problem is ongoing!!!!!!!!!!

i am running my computer on windows 7 Pro X86. And the problems is that doesn't matter what media player i use and no matter what type of files i try to play they start to play for about one second then automatically stopped. but if i switch the media player to background then they can play the file till it finish. so far i have tried windows media player VLC KMplayer Real player and quick time player. the file i have tried are mp3 mp4 flv mkv wma wmv avi 3gp and ape.

a funny thing i notice is that when i move my mouse to the minimized windows on taskbar, the preview only flash out for a short time then disappear even i don't move my mouse, not sure if this has anything to do with my problem though.

btw my computer is now running on a freshly installed windows7 so i assume there should not be any virus thing.

Maybe should have a problem with codecs.
Read and install it:
Codecs: frequently asked questions

Codecs
K-lite

shark007