I've read about this before, that error coming up apparently has something to do with Windows Installer getting stuck and for whatever reason thinking there still is an update in progress which hasn't finished yet.
A common suggestion to try and fix this involves making a change to the registry, so if you feel comfortable to do that,
here is one suggestion of a workaround.
The article in MS's
knowledge base is a little bit more of the callcenter
let's try this and that and see if you can still reproduce the error variety, but the discussion below also links to the blogpost above, and there's a bit more discussion about possible alternatives if that doesn't do anything, as well.
Maybe that can help you some of the way.
