Sorry it is Sality and it does find it, but it can not remove it properly at all.. can not remove or disinfect it. It just kept comming back
Why can't it be removed, etc. what errors/warnings are you getting.
Files in use or in system folders (even malware) is protected by windows. If you have XP you can schedule a boot-time scan from within avast (not available in Panda as far as I'm aware). Or if win9x/ME boot into safe mode and run an avast scan from there.
Where was it originally detected, file name and location ?
Where does it keep coming back to, file name and location ?
What avast provider detected it, what were you doing, browsing, downloading, running an on-demand scan, etc. ?
It could be that there is another element that is restoring that virus, but we have little information to go on.