A clue maybe, nothing is reported as being scanned. I enabled everything to be reported and get this:
A few scans, of the files that should be detected and one of them (last) was a random image on the desktop.
From what I can tell, it is not scanning any files.
*
* avast! Scan Report
* This file is generated automatically
*
* Scan name: Scan from Windows Explorer
* Started on: Sunday, May 15, 2011 11:27:03 AM
* VPS: 110515-0, 15/05/2011
*
Infected files: 0
Total files: 0
Total folders: 1
Total size: 0.0 B
*
* Scan stopped: Sunday, May 15, 2011 11:27:03 AM
* Run-time was 0 second(s)
*
*
* avast! Scan Report
* This file is generated automatically
*
* Scan name: Scan from Windows Explorer
* Started on: Sunday, May 15, 2011 11:28:10 AM
* VPS: 110515-0, 15/05/2011
*
Infected files: 0
Total files: 0
Total folders: 1
Total size: 0.0 B
*
* Scan stopped: Sunday, May 15, 2011 11:28:10 AM
* Run-time was 0 second(s)
*
*
* avast! Scan Report
* This file is generated automatically
*
* Scan name: Scan from Windows Explorer
* Started on: Sunday, May 15, 2011 11:28:48 AM
* VPS: 110515-0, 15/05/2011
*
Infected files: 0
Total files: 0
Total folders: 2
Total size: 0.0 B
*
* Scan stopped: Sunday, May 15, 2011 11:28:48 AM
* Run-time was 0 second(s)
*
*
* avast! Scan Report
* This file is generated automatically
*
* Scan name: Scan from Windows Explorer
* Started on: Sunday, May 15, 2011 11:29:09 AM
* VPS: 110515-0, 15/05/2011
*
Infected files: 0
Total files: 0
Total folders: 0
Total size: 0.0 B
*
* Scan stopped: Sunday, May 15, 2011 11:29:09 AM
* Run-time was 0 second(s)
*