XP-Pro-SP3 with RC1 build 950:
I ran Registry Cleaner and played a while with the 'Fix' and 'Delete' buttons in the result list:
1. I did not (yet) encounter a situation where the 'Fix' and 'Delete' buttons did not respond!
2. The warning message that is supposed to appear only on clicking the 'Delete' button, sometimes does NOT appear and sometimes appears on clicking the 'Fix' button.
3. Attached is the Debug Log of this test session.