Hi...
What 'player' are you trying to use ?
Have you recently installed a new player or CODEC Pack ?
Your problem is probably related to CODECs - COderDECoder = CODEC !
The link I am going to give you is safe... Really.
If you do follow the link, be sure to download ONLY the Standard Pack Of Cole2k Codecs.
Do that here >
Cole2k Codecs
Definitely choose the Easy install.
You don't need the toolbar on offer.
The installation is very fast... There is absolutely nothing for you to do except Shutdown your computer as soon as the Cole2k pack is finished installing.
Start again and you should be able to watch just about anything.
Also, try the WinAMP basic player and/or VLC. WinAMP is far more versatile... VLC has a very basic chunky-plain vanilla look... Both work very well !
So, what are you using ?