Need help! Black screen with comp still on...

Hi all,
Havent had any probs with computer for a while now but last couple days while playing Path of Neo, and then today while just sitting idly in windows or browsing, screen has gone black, but the computer itself is still on. When i hit the restart button it tries to restart but just sits there blinking the dvd's lights and not doing much else. I have to actually turn it off and then on again. Even then a couple of times, it has loaded into windows REALLY slowly.
Any ideas?
I'm running a AMD 3000+, 6800 with all pipelines unlocked, and 1gig ddr ram.
Someone elsewhere had suggested for a similar sounding problem that dust acumulation could be a likely culprit (leading to increased temps) so i've tried to get rid of as much as i could - any tips for that (i've got three fans on the case and two on the GPU plus the normal one on the CPU...)?
Any help much appreciated,
Cheers,
dave.

Dust accumulation/high temps will shutdown the CPU if the problem is that bad...not just kill the video while the PC still runs.
Try reinstalling the video driver.

Watch your hard drive, if everything is running really slowly; hopefully it's something else and not the drive dying.

Well its not doing at all yet today (!?), but i checked in rivatuner the temp (which is fine) but it says the core clock speed is only 11.32?? It should be like 350 or something at least shouldn't it?

Clocker - it seems that it not only kills the video but everything - like its in standby mode or something...no sound, no controls, nothing...

eli2k - hard drive seems fine - ran check disk on c: (main drive) and seems to be no probs there..

Any other ideas?
ta.

Well, have you tried switching out the GPU for another card to see if that's the underlying problem?

that helped my problem before, check it out

I havent been able to get another GPU to try but it hasnt done it now for a few days..
I've been playing path of neo no probs, but it still says the core clock is only at 11.32MHz in rivatuner.. Surely it wouldnt run properly if it really was...?