Shaking or lagging? If shaking, pls dont watch porn anymore yan. Lagging, well..mainly coz of paging file memory n all those shit. Nt enuff free memory to run the videos..u have too many applications or something. Or low disk space..dunno. Try clearing yer norton protected files if any n run scndisk n clear away the useless stuff. Especially ur temp folder. Either tht or u can take a risk n try changing the paging file memory system. Or ur graphics might have problem..