after downloading an "adult" movie, when I go to open with windows media player, i get pop-up ad wanting me to download a certificate, or buy a subscription to the site. it happens every time. is this a potential adware virus or something? has anyone else had this problem? if so, what can I do about it?

probably would be a good idea to just give up on that one. Any time anything pops up and asks for something it's always good policy to toss it in the recycle bin as quickly as you can. If not before you know it your comp will be eaten up with adware and spyware that will cause enough pop ups in the future to drive you mad. There's not a file out there that is worth that much of a headache.