Direct 3D constantly occupied

My machine seems to have some application that is using Direct 3D.

Whenever I start up a Direct 3D application (game) it gives me an

error message about it. I've tried reinstalling the drivers and the

Direct X itself. I've also tried browsing the processes and trying to

kill off anything stray, but no luck.

Is there some simple way of fixing this? At the moment, I think I

might be down to reinstalling the operating system.

Peter