I did get a message like this one(?) on one test install. I think it was the same - and I think I deleted all tables from my database, deleted install folder from server, cleared my cache and re-uploaded fresh install folder.
I admit I wasn't paying too much attention to the details, as I assumed I had made a mistake. You have probably done that same sequence already, but just thought I would chip in with some useless info, as is my wont.