I'm sorry you ran into trouble. The original poster of this thread and you are the only ones who have reported this sort of issue with VS SP1. We've never run into it here and we all run SP1.
As we explained in our previous reply, our installer hasn't changed in quite some time in anything related to VS. In fact, we reduced the VS-related code in the installer in 2011.2 so there should be less of a chance for any issues than before if anything.
We'd certainly try and sort out what could be causing this. It's rather tricky though since we can't see it ourselves. You mentioned the FileNotFoundException on Microsoft.Practices.Composite.Presentation. That is a Prism 2.2 file. We only have one assembly (ActiproSoftware.Docking.Interop.Prism.Wpf.dll) that references that, but nothing in our designer assemblies should. So if you didn't reference that assembly then nothing from us should be causing that.
SledgeHammer01, do you recall seeing a similar message?
Also can you give us more detail on where you saw the VS saying SP1 needed reinstall? Like when exactly does that show and what was the exact message?
We've done some internet searches on Microsoft's forums for this sort of thing but haven't come up with any results. It would help to have an exact error message to search on.
Yes, any time you change a major/minor version (like from 2011.1 to 2011.2), you do need to use a different license key. You can get the license key from your account.