I'm going to choke an infant.

I started up my computer this morning with no problems. It's the first time I've done so since Friday (I was out all weekend).

For some terribly odd reason, I cannot start any media (audio/video) programs, or FFXI.

Now, I've checked the Event Viewer, and I haven't found any errors or warnings. I've done a malware & virus scan, but they cannot find anything.

What could possibly be the problem?

What are the kinds of error messages are receiving? Hard to do an analysis just by knowing that they've ceased working.