Ah no, not again Vista and 7 with their handcuffs everywhere :-(
Now wanted to point you to the FAQ, and must find, this isn't actually in it!
Hey Guenter or whoever, please add...

Unless I'm blind...
Anyway, you must set the writing rights for your profile folder manually on those systems.
And if you have the browser just installed, a VISTA/7 restart sometimes seems to help too.