Question about CCleaner re Firefox

I used to use CC all the time, several years ago, but about 18 months ago, I ran CC using the default settings (I know, my fault) and it totally messed up my profile on Firefox to the point that it was unrecognizable, and was having trouble navigating anywhere inside the program.

Anyway, I wound up creating a new profile, and discontinued the use of CC.

The reason for this post is this: First, was the problem that I specified recognizable to any of the admins/regular forum members, and was it a one-time glitch type of thing?

CC has an excellent reputation, and I would like to use it again, perhaps someone could furnish some caveats and cautions to use for a relatively new user.

How aggressive is CC in cleaning the registry? I have heard from many that registry cleaning (by any program) should be approached carefully.

Comments? And thanks...

That doesn't sound like anything I've ever experienced personally, and posts about CCleaner destroying entire firefox/chrome profiles are few-and-far between.

Ccleaner is fairly light on the registry cleaning, but it should still be approached with the utmost caution and backups made.