Problem with sound

:sad:
Windows media player is displaying error 'The specified module could not be found.' I can not play cds-dvds-or streaming videos but I can use Itunes without any problems. I tried using Real Player 10 but I get a message that quartz.dll is missing. I ran my virus scan and spyware programs (computer Associates and Yahoo antispyware) and found nothing. I even took the computer back to factory Settings (hp pavilion a805n) with no luck. Any advise would be greatly apprieciated.

Help!!!