I have just downloaded CC with the intention of doing something about all the "temporary" internet files that have accumulated on my hard disk. I see that the program will do far more than remove just these. Much of what it does I, as a relatively inexperienced user, can only guess at. I am worried that if I give CC free rein it may take out files and things which I will regret missing later through ignorance. Is there / can the providers create an idiot-proof "safe mode" that folks like me can click on in the knowledge that no damage will be done even if it does not remove every possible redundant file as effectively as the full program? [Whenever the word Registry crops up I hit the panic button]
Creating a safe mode for CC really isn't necessary. As long as you avoid the Tools button for now, you will be fine. Those are the only items that can somewhat adversly affect your system.
Theoretically, messing around with Issues could cause some problems, but two things to keep in mind:
1. Issues in CCleaner is extremely stable; I have yet to see any OS or app compromising bugs
2. You can always make backups, so even if you do screw something up, restoring your backup will fix it
If you are hesitant, try selecting one category of items at a time and use Analyze to see what gets selected for deletion. Nothing will be deleted until you hit Run Cleaner.
With Issues, even after you hit Fix selected issues, it offers an explanation for each item it selects for deletion and gives you another chance to decide (and as lokoike pointed out, you can backup the registry items anyway).