Things such as this always scream "heat problem", so check for that first. Then check for any driver conflicts in the device manager, and then update any drivers. Next clean your computer for spyware/viruses, just because you never know.
i think its a heat problem on my graphics card, im not sure wat my graphics card is meant to run at but its running at bout 45*C to 47*C at the mo. its an Inno3D NVidia GeForce FX 5500 if ur wondering
any ideas how to fix it, or at least cool the graphics card, ive tried taking off the side of my case but no luck
taking of the side of the case can often lead to problems because most commercial computers are designed with airflow in mind. Now, if you set up a little fan to blow into the open case it would help a little, but there are all kinds of complications with that, including messing up the processor fan rotation, or blowing dust, hair, or other things into it.
You don't have one of those overclocked GPU's do you?