**WARNING: THE FOLLOWING WILL COMPLETELY DESTROY DIRECTSHOW
   PLAYBACK ON YOUR SYSTEM IF YOU DO IT WRONG.**
**YOU *MUST* DO THE EXPORT STEPS AS THIS WILL BE ONLY WAY 
  IN WHICH YOU *MAY* BE ABLE TO RESTORE DSHOW IF THE LAST
   STEP DOESN'T WORK.**
**THIS WILL DISABLE AND REMOVE *ALL* THIRD PARTY FILTERS
    ON YOUR SYSTEM.**
(However, since these usually are what causes Really Bad 
  Things to happen, that's likely a good thing if you're at this stage...)


1. Export "HKEY_CLASSES_ROOT\Media Type\{e436eb83-524f-11ce-9f53-0020af0ba770}" via:
 Open regedit.exe
 Go to "HKEY_CLASSES_ROOT\Media Type\{e436eb83-524f-11ce-9f53-0020af0ba770}"
 Select "Export Registry File..." from the Registry menu
2. Export HKEY_CLASSES_ROOT\CLSID\{083863F1-70DE-11d0-BD40-00A0C911CE86}    
3. Delete both these registry keys.
4. On Windows 95 or NT4, reinstall WMP6 on top of your existing WMP6 install.
   On Windows 98OE, 98SE, Me, Windows 2000, reinstall WMP7 on top of your existing WMP install. 
     Use the offered reinstall mode.  If you were using WMP9, then reinstall WMP9 on top of your
     system.
   On Windows XP, run the steps at
      http://zachd.com/pss/pss.html#wmp8repair

This will nuke your DirectShow Filter database and restore it as best
  I know how.  You should only lose third party filters with this method.