DirectX freezes when in use

Hi all,

I have a NVidia RIVA 128 AGP graphics accelerator in a Win98SE system. When I am playing games that use DirectX, it freezes. This also causes the sound card to produce a high-pitched beep noise. I cannot get my system out of this state without a reset or power cycle (no Windows hotkeys work at all) and I have tried everything I know. Here's everything I know right now:

The problem isn't in the graphics card itself. I know this because a) I've used this card in another computer before and it never did this and b) it works fine in Windows (non-DirectX games work).

The problem may be in the driver, but I doubt it because a) I've used this particular driver in another computer before and it never did this and b) it's the latest driver available from NVidia.

The problem has to be with DirectX, but I downloaded the latest version (DirectX 9.0c) from the Microsoft site. I have gone through all pages of the DXDiag software and none reported any problems, except that it didn't want to use the graphics driver because it couldn't connect to the 'net to get the info on the driver to see if it was signed or not. That computer isn't hooked up to the 'net.

The problem was occurring both before and after a format/reinstall of Win98, so it must be software or a damaged mobo. I would like to think it's software, though.

I shut off all hardware accel in the Control Panel>System>Performance>Graphics screen, and it didn't fix the situation.

I'm baffled + frustrated, so please post back soon. If you need more info, let me know.

Meanwhile, I'm going to keep playing with it. I know it's an old accelerator, but I had it working before and I want it to work again.

Thanks in advance,
Jacob