Computers need re-start to get online

[ronaries]

Hi. My household has a D-Link router (di-624) and sbc DSL - and two desktop(s) repeatedly require rebooting as they lose the internet connection after about 30+ minutes of non-use. Hibernation has been turned off in all. The 3 desktops are hard wired to the router, all using Win XP SP2 (1 Home, 2 Pro). One is connected thru a hub.

I have contacted both Compaq and SBC about this problem, and made minor changes, but to no avail. Curiously, my older computer - the non-HP one - does NOT lose the internet connection. The difference between this and the other 2 computers is that 1) its not an HP product, and 2) it uses Sygate instead of ZoneAlarm as the firewall.
When the 2 desktops lose the internet connection, I have tried closing ZoneAlarm ...the connection has then been restored, but I am unable to surf to different urls as it hangs up and I have to close the browser...which is Mozilla Firefox, upgraded to current date.

Also, I have an HP Pavillion laptop, XP Home & sp2 &Firefox and ZoneAlarm, which DOES NOT lose the internet connection when not used for 40 min or so - go figure!

Tips on this problem most appreciated - I am experienced PC user , but novice at networking.
thanks!

[glc]

Uninstall all those firewalls. Your router is a hardware firewall. The XP SP2 firewall is a good second line of defense. Sygate and Zone Alarm are overkill.

[ronaries]

Thanks , GLC. If I uninstall the firewall (zonealarm), do I need to specify anything on the router setup to make the firewall effective? There were a lot of setting choices on it which I never utilized since I didn't understand them well. Also, I do not have the Windows XP-SP2 firewalll active.
Thanks for clarification.
Ronaries

[glc]

No, the router firewalls due to NAT (network address translation). Enable the SP2 firewall.