Hi WhiteCube, and welcome to the eForum!
This does sound strange, but does appear to be an error on your Windows side of things. I'm not Microsoft Accredited so can't advise an in-depth walk-through on how to resolve this, but from previous 64bit incarnation (Vista, XP) issues, I can say that fixes in those cases have not been quick or easy.
I will have a word with some of our Windows experts to see what we can suggest if anything at all. In the meanwhile, perhaps some of the community can help?
I always recommend saving a recent restore point just in case anything goes awry!
Let us know how you get on.
Daz
eForum Team