Questions about registry scanner

CCleaner for Windows
1

I have a few general questions about the registry scanner. There are several results that I'm not sure are safe for me to delete. One example is an "unused file extension" error with the .PDF extension. I'm not sure why its labled as unused since .PDF files on my computer are currently associated with Foxit Reader...

Also, there are several "open with application" issues for programs that are currently installed on my computer; they have not been removed. Is it safe to fix these kinds of errors? Thanks in advance!

2

No one has any input on this?? Come on, there's a lot of knowledgeable people here! :D

3

I just fix all - backup as the app says, and you will be able to restore if you do bugga up something.

Normaly when i run crap again, it picks up the same errors, like .bsp - even though it has a backlog of assaigned apps such as half-life 2, half-life, quake, sin ep's, etc, etc. it still says 'unasaigned'