Weird comp freezes

[VeZ]

Well in the last few days my comp has been really messing up. It only happens so far when im on the internet. Im just searching around and bam, my mouse and everything freezes up, cant ctrl alt delete or anything..so i am forced to shutdown. When i power it back up, right before the login menu should show up, i just get a black screen, and it stays there, and doesnt do anything, so i try again..same thing...so usually after about 5 tries my computer actually works. Ive already done virus and tons of spyware checking, so any other ideas?
Athlon 64 3000+
Nvidia 6800 LE 256mb
512 pc3200 ram
420 PS Thermaltake

 

[MrChad]

Check your temperatures?

 

[VeZ]

temps are fine, i checked it a few days ago after the first time it happens, besides im barely using up any proccessing power
CPU : 35C
Video : 58C (normal for the card i have)

Oh yea and sometimes when it goes blank before login screen, it acts as if its going into hibernate mode or sleeping

 

[VeZ]

k just tried to restart, once it got to where it should be log in screen, there was a block of just a bunch of weird colors, could this be a problem with my video card? I had troubles with it when i first got it but that was in novemberish...could this have to do with my vid card being stupid and dying out so fast?