Ok the vps update package that I am currently using is 83.8 mb dated 5.8.2013 …

OK for one moment I believe that “The problem is the ‘incremental’ virus definitions update can’t handle the difference between what is in the database in the old installation file (be that avast5 or avast6) and what the current virus definitions database contains now.”
Dude kindly go through previous posts I have clearly written that the same vps package and the same avast version 6.0.1203 has worked once couple of days ago … WHY NOT IT IS WORKING NOW ???

LEMME TELL U WHAT I BELIEVE …According to my knowledge the avast vps package contains databases from very beginning to the present day .
Same vps works for version 5 which has much older databases than version 6 … If it works for version 5 that means it will definitely work with version 6 because version 6 has been built after version 5 , and version 6 already contains newer databases as compared to version 5 …
Let me tell you that IT HAS WORKED ONCE …tell me WHY IT IS NOT WORKING AFTER RE_INSTALLATION ??? If somebody have answer to this question then its well n good …if not the I have one last question Like Avira has database fuse bundle updater tool & Kaspersky has Database Updater Tool … DOES AVAST HAS SOME UTILITY THAT CAN BE USED FOR OFFLINE DATABASE UPDATE AFTER THE RE-INSTALLATION ???

Regards
Atul