Computer glitch/slow-running/I dunno

[LimitGod]

My computer out of nowhere has a certain "glitch" to it. The best example I can give is that when dragging my mouse across the screen it stops for a split-second about every 1 or 2 seconds.

Also, watching any type of movie/youtube/downloaded file is sketchy as well. Even the deal of the cards on Pokerstars has the glitch to it.

I noticed my C: drive was about 80% full and I just deleted over 15GB or files/movies/etc... from my hard drive and still no solution. I've run all of my anit-virus/spy/mal/etc...ware and the error is still there. Any ideas?

I appreciate the help