… And I have no idea what to do now… 
Any tips???
Regards, noro
Did you run the installer as Administrator (that is, using that option, not just while logged in as an Administrator)?
You mean by clicking right mouse button? If yes, yes, even this way…
see: Why won't SketchUp Install? - #5 by DanRathbun
For some reason you do not have write permissions to the FeatureControl attributes in the registry.
Are you logged in as member of the adimistrators group ? … or just a normal user account ?
See: How to Geek: Enable the hidden administrator account on windows
Thx guys, for your replies. In this case I had to select special permissions in MAIN folder in IE… Works fine… 