gregrocker said:
I use the CCleaner "Run Cleaner" and Registry tab, followed by the also-state-of-the-art Auslogics Disk and Registry Defraggers, after an install is completed and then about every month.

A good rule of thumb is if you have to wait long for it to complete, then run it more often.

[If it gets bogged down with temp internet files, then check "Empty temporary folder when browser is closed" in Internet Options>Advanced.]

In ten years of installing on hundreds of machines, and knowing dozens of others who have used it regularly, the CCleaner has never presented ANY issues. It simply doesn't seem to make mistakes, probably a tribute to the genius behind it.
I agree. Never had any problems with it.