Win32 rootkin gen. Need help

Got a alert that a Win32:Rootkin-gen had been found on my computer. Did a full system search with avast, but didnt get any hits. False alarm?

What is the infected file name, where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ?
Check the avast! Log Viewer (right click the avast ‘a’ icon), Warning section, this contains information on all avast detections. C:\Program Files\Alwil Software\Avast4\ashLogV.exe

What action did you select when it was detected ?

When did this happen, routine on-demand scan/on-access scan/shortly after boot (8 minutes) ?