I've been running the various 2006 RC's on a laptop without problems.
Today I decided to test running it (RC #4) on my desktop and had problems with the registry cleaner. It basically didn't want to stop running. It went through roughly 45,000,000 items ( .. is it looping back through the registry ??), with lots of HD I/O, before Win XP generated an error message that it was running low on virtual memory. CTRL-ALT-DEL wasn't able to shut down the JV16 process, and the computer locked up. The desktop PC has AMD64-3000 CPU, with 1G of RAM.
Has anyone run into this sort of thing?