OK, I have done a number of further tests, disabling startup programs, rebooting and checking the Standard Shield scanned total after boot.
Disabled ProcessGuard Free Reboot Scanned Total: 803
Disabled SnagIt7 Reboot Scanned Total: 829
Disabled Outpost Pro Reboot Scanned Total: 833
No changes to maintain a stable registry and reboot Scanned Total: 783
So even after disabling the three programs (startup entries) mentioned there is no noticeable difference, certainly not one that would account for the excessive scanned total after boot.
Disabled SpywareGuard Reboot Scanned Total: 777 again no negligible difference.
Checked Windows Services and found ProcessGuard and Outpost still had services enabled on Automatic. Ended the processes, changed to Disabled and rebooted - Scanned Total 303.
Enabled Outpost Services on Auto and enabled Outpost Startup item and reboot - Scanned Total 803, bingo it looks like I have found the culprit Outpost.exe. I have no idea what or why Outpost should access a large number of files on the HDD. I have looked into the various settings in Outpost but can find nothing that may cause this.
Now what to do about it as I think it essential to have Outpost run on boot, otherwise I would have to manually start the outpost service and the startup entry. With Outpost completely disabled the scan in the low 300s reduces the time the avast icon spins. If I start Outpost the scan count jumps by 450-500, but this only takes a few seconds, the additional files that are being scanned after boot take considerably longer.
I had filemon enabled as a startup item so I have filtered occurance of outpost.exe, but that doesn't tell me much but it keeps accessing op_data.mdb. It may be possible that the contents of this file are accessing the files to check for changed content? I don't know I have no way of opening the .mdb file other than with a text editor and that returns little useful (to me) information.
Do any of the Alwil test systems run Outpost Pro and do they suffer this increased scan activity?
Any further information/suggestions, perhaps excluding outpost.exe and or op_data.mdb in avast4.ini (but where)?