I purchased a Media Center PC some time ago with the following: Intel Pentium 4 2.53GHz Nvidia GeForce4 MX420 (64MB) 512MB DDR SDRAM DirectX 8.1 Everything ran well until after I installed DirectX 9.0. Then, the Media Center app (and basically anything that uses 3D graphics) started flashing green and white with lines or random sharp angular pieces. Recently, I checked DX Diagnostics, which said that I was running a debug version of directx.cpl. I tried to install DX 9.0c again, but it didn't solve the issue. Today I decided to try to fix my old computer again, so I used DirectX Happy Uninstall to revert to the original DX which came with the PC (8.1), and the problem seemed to be solved. DX 8.1, however, didn't have Direct3D available in DX Diagnostics. So I followed DirectX Happy Uninstall's directions to update DirectX to the latest version (with the DirectX 9.0c Redistributable installer). After I did this and I checked DX Diagnostics, directx.cpl was no longer the debug version and it stated there were no problems. Then, I performed the Direct3D test a few times, and it failed for Direct3D 8 and 9 Interfaces, and occasionally even for Direct3D 7 interface test. Does anyone have any idea what can cause this issue with Direct3D and/or how it can be fixed?