I had major problems trying to remove .NET 2.0 it did not show up in add remove programs, and I could not uninstall it using the Windows Cleanup Utility.
I tried this utility to remove .NET 2.0 and it worked perfectly and allowed me to reinstall .NET 2.0, however this utility should be used in extreme cases and should only be used when all other methods have failed. It also works with the following versions 1, 1.1, 2.0, 3.0, 3.5, 4
Use with caution, we accept no liability for its use.
You can download it from here