I also got the very same Problem with Netbeans 7.1.1 on Windows 7 x64.
The solution was:
change the security-level to full access for the installation- and all subfolders. Then it finally worked.
As i didnt find the solution on the web for over a week (also tried re-installing, different computers with same operating system etc) i guess there's currently no developer working with Netbeans under Windows 7.