Can't clean Firefox 3.6.12 cookies

Basic info:

Operating system: Windows 7 64

CCleaner version: 3.00.1310 64bit, tried downgrading to latest 2.XX builds

Firefox version: 3.6.12 (latest stable)

Hello,

CCleaner ceased to see any Firefox cookies lately, i.e. I have none of them listed in "Cookies to delete" field, and it doesn't clean any of them. I can see them all in Firefox (the ones I want to keep and also have on "cookies to keep", and a lot of others I would like to get rid of).

I've seen few topics about latest builds having problems with Firefox cookies, but the solution was usually to close Firefox or uncheck index.dat in CCleaner. Well, I always close the browser before using CCleaner (not running in backgroud as a process) and tried uncheking cleaning index.dat files. Unfortunately it didn't help.

I'm not sure when the problem started, but I guess it would be the latest 3. builds. Tried to downgrade to previous builds with number 2, but it didn't help.

---EDIT---

After reinstalling Firefox (deleted preferences and "leftovers" in Documents and Settings folder) it works like a charm. Unfortunately I'm not sure what exactly caused the problem.