Nobody reads my posts
1. Upgrade to Direct X 9.0b
2. Visit Windows Update and download all critical patches
3. Upgrade to Service Pack 1/a if at all possible, or at least download every critical patch available from WU and see if the problem persists.
4. Update your video card reference drivers, but make sure they are official drivers. Do not run the risk of running an untested (or leaked) driver for your graphics card, unless you know what's going on.
5. List your hardware details and configuration, as Winston has said. Preferrably any installed software (legally obtained), as there may be, as I have noted, software conflicts, not to mention any possible hardware conflicts within the system.