I've noticed this occuring on several machines I have recently worked on whom have just had CCleaner installed and even updated. The progress bar will continue to loop until everything is actually deleted. In the Task Manager under Processes, I have seen CCleaner take up as much as 135,000 K of memory, if not more. The results of the cleaning have been anywhere from 45MB - 500MB.

MrG wrote about it restarting here.

True, though it could be like with registry issues. It goes through once but shows you the progress bar and the percentage.