I downloaded a video and tried to play it on WMP (I think I have 11 on this computer I don't know what version Vista Home Premium has) and I can't play the file instead it's telling me to check my sound system and all software associated with it.

Having done what it has told me everything appears to be up to date all sound systems are enabled and in working order and yet still I can't play this file.

Any ideas what can I do? It's really frustrating!

You really haven't given enough information. What format was the file in? Is it something Windows Media Player can play? Can you play any files successfully? If so, have you played any files of that type before?

I'd try another video player, maybe VLC media player

The file is a WMV which should be compatible with Media Player

Should be, but not necessarily - it might be misidentified, or it may need codecs (special video drivers) that your PC doesn't have. What is the actual error message?

I figured out the problem. It was the external hard drive I had save it on that caused the problem. Thanks for the help!