FireFox & Mozilla Cache Is Skipped

Tonight for the first time I received this warning while using CCleaner (up to date version I checked):

You must close Firefox/Mozilla to allow the internet cache to be cleaned. Otherwise the process will be skipped.

And it was skipped..

I don't know what the problem is. All Firefox/Mozilla was closed. The only difference I know is I use MS Outlook Express & Internet Explorer 7.0 also, along with Firefox at times. I updated Internet Explorer to 7.0 from 6.0 version. I have e-Trust Security Suite with anti-virus, anti-spam, firewall, anti-spy. I have had that all along & has caused no problem before. Any suggestions appreciated.

I use Windows XP (Home)

Its a firefox issue. Sometimes when you close firefox its process hangs and doesn't really close. Its very easy to fix though. :D

Press ctrl+alt+del to open the taskmanager. Click the processes tab and then search for firefox.exe , once you find it right click it and choose end process. Now try to run ccleaner.(make sure there are no firefox.exe listings.)

Edit - what rridgely said.