avast.setup needs to have access otherwise no updates.
Based on your VPS file version of 0511-1 your VPS file is well out of date - the current VPS version is 0515-0, so your program may well be out of date - the latest release version of avast is 4.6.623.
I would suggest that you try a manual update and see if your firewall asks permission for avast.setup.
Also I would suggest that you try a repair of avast. Add Remove programs, avast! Anti-Virus, Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.