I tried to upgrade from Vista (64bit) to Windows 7 and it got up to generating compatibility Report - which was completely blank. The only way to proceed was to hit 'Close' - which then cancelled the installation!
Previous to this, I had also tried to download & run the Upgrade Advisor. When trying to run it, it just did nothing at all - didn't even open up. I disabled my Kaspersky anti-virus and disabled any Windows security. I was trying to avoid doing a clean install - but maybe only option. Any ideas?