I had Visual Studio 2005 Team System Beta 1, Team Foundation System CTP, and SQL Server 2005 Beta 1 installed. I uninstalled them following the directions of Rob Caron and MSDN's official uninstall. The former is really the guide to installing Team Foundation Server.
If you get this error trying to install SQL Server 2005 Beta CTP, go into the redist folder on the CD and click on the dotnetfx.exe. That will give you the actual error.
My problem was that it wasn't recognizing that I had uninstalled “Microsoft Visual J# .NET Redistributable Package 2.0 Beta.” For some reason it was still picking up the key in the registry even though it no longer existed on my computer.
Delete these keys and any subkeys below them.
- HKLM\SOFTWARE\Microsoft\JSharp
- HKLM\SOFTWARE\Microsoft\.NETFramework\v2.0.xx
Delete Any reference to J# in this folder
- HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders
Delete any keys with reference to (where it is the only reference or it speaks of install packages)
- JSharp that has Framework\v2.xxx.xxxx in the reference (C01F64097E5F1784EB9D288881FC907FD on my machine)
- J# that references the same framework as above.
Once that is finished, it should work okay.