Audio runs fine video slow laptop Vista 64 bit

I've had this problem for about a week now. Audio runs fine but video playback is sluggish if it plays at all, usually i just get audio and a frozen screen. Typing and opening windows explorer takes forever. Any kind of response is sluggish at best.
no matter what I have open, task manager says cpu usage is from 80-100 percent.

I'm running vista 64 bit on a AMD Turion X2 dual-core mobile rm-72 2.5 GHz

I have run my anti-virus/malware software, nothing found.

I'll be the first to admit that I have no idea what I'm doing, or whats going on with this thing, but any tips would be greatly appreciated.