I'm sure it is not a virus

[rimati]

I'm sure it is not a virus. Only today after updating wiht the new home version, a file that I have often used and that was downloaded from other people, is detected as a virus. 

[DavidR]

Your sure what is not a virus ?

What is the malware name, 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
 
- Or check the source file using notepad C:\Program Files\Alwil Software\Avast4\DATA\log\Warning.log and copy and paste the entry.

[rimati]

19/08/2009 21:41:36   SYSTEM   1752   Sign of "Win32:Induc" has been found in "D:\flashs récepteurs\fte\USB\KeyEditorFTE v1.2_pour alii b_c_e\KeyEditorFTE v1.2_pour alii b_c_e\KeyEditorFTE v1.2.exe\[PECompact]" file.

[mkis]

Consult this thread -- http://forum.avast.com/index.php?topic=47773.0