Intel Celeron 2.66 Ghz CPU windows XP Professional SP2. Unable play any media (movies etc)especially AVI files. As soon as I click the file (right click or left click), I get the following MESSAGE warning QUOTE " DATA EXECUTION PREVENTION. - TO HELP PROTECT YOUR COMPUTER, WINDOWS HAS CLOSED THIS PROGRAMME. NAME WINDOWS EXPLORER FOLLOWED BY A CAPTION 'CLOSE MESSAGE. After clicking the close message caption, the standard message comes up viz., Windows Explorer has encountered a problem ----- etc" my SECURITY CENTRE is working well. All the 3 are indicating ON. Anti Virus (avg & Avast) uptodate. Also have Spybot & Advanced Window care personal V2 personal installed & carryout regular checks. Pls advise soonest. Thanks & regards. VITUS.