cant play .mp3 or .wma in media center or WMP

I already installed the codec pack when this wouldnt work initially, and then installed winamp, which plays either file just fine. Any ideas?

After installing Windows 7 two days ago I could not play any MP3, even those that came with the player. I have an Audigy 2 Platinum and this is what resolved the problem for me.

1. From the Windows Desktop, right click the Speaker icon on the right side corner of the Windows Taskbar.
2. Select Playback Devices.
3. If a problem exists you'll probably get a message about an audio enhancement problem. Click no.
4. In the Sound window, Select Speakers or default device and click Properties.
5. In the Speakers Properties window select the Advanced tab.
6. Uncheck Enable audio enhancements.
7. Click OK or Apply.

This solved the problem of not playing MP3s on my box. I hope it helps anyone else having problems. Mileage may differ according to your sound card or device.

Oh, I also have disabled the motherboard onboard audio.

may be your pc have virus in it