Which program are you trying to use to play MP3 files? Could be that this application needs to be un/reinstalled. If you're getting any specific error messages, post them verbatim - that'll make it a lot easier to figure out.

You may also have too much junk running at Startup - for information on this, and how to correct it, go here.

I have uninstalled all the audio stuff except adaptec CD Creator and Windows Media Player. Now when I try to play a mp3 it says that "PlayCenter cannot find hardware or drivers.Please check your hardware." I found a problem in Device Manager. Under the "Other Devices" icon there is a listing for the PCI System Management Bus and a listing for Unknown Device both of which has a yellow !. Under properties it says there is no driver installed. How do I go About installing drivers for these devices? And how can I find out what the unknown device is?