Windows Media Player for Windows 7 Professional Freezing when opening

There are several scenarios. When did this error occur, was it recent? You can try a System Restore to revert your settings when WMP was working fine.

Another alternative is to download CCCP codec pack from here:

http://www.cccp-project.net/

Then you can use Windows Media Player Classic.

You can also download VLC player which works on nearly all formats:

http://www.videolan.org/vlc/index.html

- Make a new user account.
- Check if the new user account has the problem.