Windows 2000 SP4 and all the critical updates since then.
From the thread you referred to, Technical, I assumed that after one adds the line
<STANDARD--ScanPackers>EXE;ZIP;MIME;RAR;ARJ;TAR;GZ</STANDARD--ScanPackers>
after the line
<STANDARD--InvalidEntry>1</STANDARD--InvalidEntry>
in DefTasks.xml file avast! would scan zip files as you click on them (This is how I see "on access", correct me if I'm wrong). Mine doesn't.
However, it shoots a virus alert at the moment I try to download eicar_com.zip. Once I "OK" the alert and download it I can click it and see what's inside the archive, no more virus alerts. Added the line to that .xml or not. What exactly this file edit gives?
Hope this makes sense this time