CCleaner is calibrated flawlessly to know which are disposable temp files. I watched it being done over 15 years. It doesn't make mistakes. There are no worries with running it. I'm growing weary of the ankle-biting.
I am a fan of CClener as well. I have used the "Cleaner" portion for years after seeing it recommended on GRC by some of my peers. It now includes a "Registry" function. Since Windows 7 has a good reputation for maintaining the registry, do you suggest it as a viable tool or better to ignore it? My opinion is to advise against its use, so that newbies don't get themselves in trouble with it.
Sorry for my exasperation but for three years there has almost always been a thread going which trashes CCleaner as though it's Registry cleaner function is suspect or even in the same league with the Reg Cleaner sales scams seen in ads which always ruin Win7.
Yet no one has ever provided a single documented case of CCleaner causing problems, and my own experience is installing it over 15+ years on hundreds of installs representing thousands of uses without a single complaint.
I don't necessarily disagree with those who maintain that Win7 in its perfection doesn't need cleaning or defragging, however I regularly clean up dirty machines which have 1-5 gb of schmutz, hundreds of registry shells, and improve performance and startup (one by a full minute) substantially using Puran free boot-time defragger. This has kept me at it without much deviation.
So I have my favorites which I feel are worth defending in spite of ridicule. I dont like to see genius trashed, and have witnessed from beta that CCleaner is a work of genius. It has earned its place at the top just as Seven Forums has.