I previously reported that the problem was fixed and upgraded to V6 Pro on two machines. It was not, but I think it is fixed with VPS 20110512-0.
I also have a net-book that I only occasionally use, with V4.8, last updated on 20110425. So I tried to update it using the manual update on the context menu (right click on the A icon in the notification area).
Choosing iAVS update downloaded 3.228MBytes of VPS files since 20110425. The install program ran and the status message at the end was "broken package". "About Avast" showed the VPS version still as 20110425. I tried to run iAVS again. Nothing was downloaded saying the system was uptodate. The status window showed the version as 20110511-1 (which is why I thought the problem had been fixed on the other two machines) but "About Avast" still showed 20110425.
I ran Program Update from the context menu. Some files were downloaded and installed. When the install completed a further VPS had been added - Compilation Date 12/05/2011 and file version 20110512-0. This was shown in both the status windows and in "About Avast". I believe therefore that this method of doing both iAVS and Program Update may have bypassed or fixed the "broken package" problem and record this in case it is of use to others.
As I find my licence key does work on V6, I am installing that on my three machines.