No, don’t worry I’m not that crazy. On the HTPC, I initially installed Vista on the 1Tb disk. When the replacement system drive arrived, I then installed Vista on that drive, but didn’t reformat the original disk as I’d already recorded some programmes that I wanted to keep.

This meant that there was the old “Program Files”, “Windows” and other directories that Windows creates. The problem is that even running with UAC you can’t delete them. If I’d reformatted the drive, I would have never had this problem.

Tim Sneath went through a similar situation, and his solution worked for me too.