Old DirectX installed over my 9.0C...Or at least part

Just for fun last night I thought I would install Quake2 in my WinXP with DirectX 9.0C and play some old style. When the CD autorun kicked in a directx window popped up and said installation was complete. Apparently it had tried and partially succeeded to install the version of DirectX Quake2 came with. The problem is that it messed up my current install making my mouse not work properly. So I tried to reinstall 9.0C but it won't install it over because it thinks its already there, which it is... almost. I then tried an uninstaller called DirectX eradicator but that didn't do anything either. Anyone had this problem, help?

Open the DirectX Diagnostic Tool by typing dxdiag in the Run box. On the "System" tab, check the version of DX installed...it should show as: DirectX 9.0c (4.09.0000.0904). Next click the "DirectX Files" tab, and look near the bottom under "Notes"...it should say "No problems found" if indeed DX is installed correctly. XP shouldn't allow an older version of DX to overwrite a newer version of the files...if it does for some reason, there's a definite problem.