well the OP was asking about conflicts between CCleaner and Avast!, so I was conveying my experience. Avast! wasn't cleaning out the files from the temp folder, had something to do with CCleaner having hooks in them. I'm pretty sure my case was a very special and specific case and won't be experienced by anyone else, but you never know - so I put it here for posterity.
I have had zero issues since I changed the settings on CCleaner and Avast! started working properly again. I changed all the settings back to what they were in CCleaner (when Avast! wasn't clearing out the temp files) and Avast! is still working properly. Just something buggy happened (probably due to the virus) and things got 'stuck' and I got the 'unstuck' by changing settings. Who knows. All I know is everything's peachy again, just wanted to add to a dead thread.