You might want to try removing avast with this application. It says 6.0.1000 is supported but it should work for 1125

http://www.appremover.com/supported-applications

edit:

you may want try this after uninstalling avast.

Uninstalling and Reinstalling the Windows Media Player:
Step 1.
Uninstalling the Windows Media Player:

  1. Go to Start and in the search type “Turn Windows features On or Off”.
  2. Click on “Turn Windows features On or Off”.
  3. Browse to the Media Features and uncheck the mark in front of Windows Media Player.
  4. Restart the computer

Step 2.
Reinstalling the Windows Media Player:

  1. Go to Start and in the search type “Turn Windows features On or Off”.
  2. Click on “Turn Windows features On or Off”.
  3. Browse to the Media Features and place a check mark in front of Windows Media Player.
  4. Restart the Computer.