Serious Sound issues

Hello,

My sound is stuttering and has static in it. All the hardware is up to date, all of it is working properly, according to device manager, I've tried system restore, I've tried disk cleanup (in case the system was just running slow), I've defragmented and deleted unused programs. I've done pc diagnostics with Toshiba, Windows, and a few independent websites. Whenever there is a video trying to play or anything that makes sound, my computer runs a little slower, sometimes freezing up.

I just went to sleep one night with my computer doing just fine. I had been listening to music, I watched a movie on it, everything was working perfectly. Then I woke up the next morning with completely distorted, stuttery, static-filled sound.

If anyone can help me, please, I'll take anything. I'm kind of computer-dumb, though, when it comes to the technical talk.