Really weird activation problem

Hello All

Really weird problem here. I installed the latest version of Scrivener (v1.9.0.0) and I installed it with no problems. However when I enter my license information in order to activate it, the programme tells me that it has been accepted but then Scrivener closes down and the shortcuts from then on do not work. I investigated and the scrivener.exe file that existed before has deleted itself! I’ve tried this three or four times now with the same result.

Please help me with this baffling problem!

Thanks in advance.