No Internet Access with Zone Alarm Stealth Mo

Hi,

I have Zone Alarm 7.0.470, Windows XP professional ( all patches etc I believe )

I have the same problem on both Desktop and Laptop via wireless router ( BT Voyager ).

I could not access the internet, but could access the router.

I have reset the router and removed then re-installed Zone Alarm.

after messing around. I know I can access the internet with zone alarm off, or stealth mode turned off

I can ping web sites if zone alarm is in stealth mode.

I am also using AVG 8, which was upgraded recently and sure all was ok for at least a few days.

As far as I can see the networks, settings are all ok, however would be grateful for any suggestions and reminders.

Thanks in Advance.

Rob