Some information wouldn't go amiss.
What Operating System are you using ?
What avast! version and VPS file (virus database) number, e.g. 4.7.1074 and 071202-0 (see about avast!) ?
What is the malware name and 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
Did avast detect it ?
What action did you choose on detection ?
Why can't you get rid of it, error messages, etc. it keeps coming back, what ?
