Hi yellowspring,
Glad you got some problems fixed. No, you don't really need media center. It's not a necessary app. But it's up to you to decide if you ever need to use it. There is a Net uninstall tool that is supposed to help with the uninstallation of the Net framework. And then you could reinstall it but I've never used it so I personally wouldn't know if it helped or not. The question you have to ask yourself though is, how did all this corruption happen in the first place. Bad installation or uninstallation of something, using a Cleaner program that deleted/corrupted some important files,etc.
Aaron Stebner's WebLog : .NET Framework Cleanup Tool User's Guide