Windows Installer Problems

I have somehow corrupted the Windows Installer to the point that:
- it hangs up shortly after starting any install or uninstall
- I have to use Task Manager to kill it
- the install for the Windows Installer Cleanup Utility also locks up
- nothing happens when I try to run System Restore

Does anyone have any idea how I can fix this without rebuilding my entire system?

Thanks

Rex Anderson
850-227-5416