MMSYSTEM266 error?

[dolph]

i get this error when i try to open some media files, and i cannot install any dvd viewing software (it hangs after i select next after choosing the installation directory).

 

[maddmax]

I think your missing an ATI codec. Try uninstalling/reinstalling the ATI multimedia player.

 

[piercedan]

http://support.microsoft.com/support/kb/articles/q139/8/06.asp

Check this MS KB article. It may be of some help.