The problem started when I decided to reinstall .NET 3.5 because of an error in my Adobe Flash Professional CS 5.5 installation. To be on the safe side, I decided to also delete the registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NetFramework\InstallRoot. I couldn't get it to reinstall, so I searched for what seems to be the default value of the previously mentioned registry key. I then entered this value, C:\Windows\Microsoft.NET\Framework, as the registry key. I still couldn't install .NET 3.5. Whenever I install it manually with the downloaded installer, I get halfway through the installation, and then I get a crash report stating setup.exe has stopped working. In addition, the .NET installer states:
An error occurred during setup. Installed files have been removed from your computer. For known errors and troubleshooting information, see the online Readme. For error information, see Error Log.
I get no error code. When installing it with Windows Update, I just get an error after a while. One thing I've noticed, however, is that if I view installed updates in the Control Panel, I see an update titled Update for Microsoft .NET Framework 3.5 SP1 (KB963707). Should that be there, since I don't have .NET 3.5 installed? When I try to uninstall it, I get error that says:
This action is only valid for products that are currently installed.
Please excuse my ignorance of anything Windows, since I haven't used Windows for over a year now, only Linux.