multiple registry scans required

Can someone explain why I need to run the registry cleaner a few times before all the items are fixed?

after the first clean I got down from ~200 problems to ~20, but only the fourth run was completely clean.

Dan

Because certain registry keys are linked. The first time you run CCleaner's Issues scanner you'll have to keep running it back-to-back until it finds nothing. One scenario is a registry key may only be a reference pointing to a completely different location in the registry and when it's removed then that reference link is also noticed as being invalid on a subsequent scan. It's generally a good idea to keep running the Issues scan until nothing is listed.