No internet after upgrade 4 to 6 through Admin console

[dubbelma]

After upgrading 60 machines succesfully in the Netherlands I wanted to upgrade my German machines and then the troubles started.  several peoples started to compain about their internet access, sometimes it's there and 5 minutes later it's gone again. After trying out all the tricks in my book I started to wonder if this could be caused by Avast. When I disable  all the shield the internet runs properly and when I turn them on all troubles.  Anyboy an idea what causes this and even better how to solve it.

The machines are all running XP Sp3 under a domaincontroller with 2003 server Standard.

Please help me??

[wpn]

maybe you can tell more about the network setup
like how the connections are, routers, proxy servers
?

[Arizona]

You need to remove 4 from add remove reboot to safe mode use avast remove tool then reboot install 6.

[dubbelma]

@wpn The network topology is a cisco pix router for internet access, followed by a HP switch managed and then the PC's. Strange is however that of the 20 PC's only 4 have troubles with Avast.