Well, I have installed Avast and all for now seems working fine. It found some viruses in some old files, not too sure whether they are false positives or not, but not being useful in any case, have moved them to the chest.
However what would be the meaning of these errors/warnings in the log file?
'28/07/2008 12:14:05 SYSTEM 308 AAVM - scanning error: x_AavmCheckFileDirectEx: avfilesScanReal of \\PC3\xxxxx Docs\TB15\Profiles\nblgiuac.default\prefs.js failed, 00000005.
and
28/07/2008 12:14:05 SYSTEM 308 AAVM - scanning warning: x_AavmCheckFileDirectEx [UNI]: \\PC3\xxxxxxx Docs\TB15\Profiles\nblgiuac.default\prefs.js (\\PC3\xxxxxxx Docs\TB15\Profiles\nblgiuac.default\prefs.js) returning error, 00000005.'
The above are only one of several entries in the log file, all pertaining to this action for the several files in the profile. I was backing up my TB profile to another PC on my home LAN, prior to scanning / checking e-mail on TB after installing Avast.