Vista - Network disconnects, requiring constant hard disconnect and re-con

Hello all,

Everytime I connect to my internet using IE or Firefox I loose network
connectivity after a long period of inactivity (15 - 30 mins). It only
reconnects if I unplug the ethernet cable and reconnect it to my NIC card.
Then it works fine.

My setup is as follows:
Internal NIC of a D915PBL motherboard connected to a Netgear Rangemax WPN824
router which then connects to a Centellium VOIP box, which gets its
connection from an Adelphia Cable Provided RCA cable modem.

In case you might suggest that the long process of getting the internet
signal is contributing to the problem:
The computer that i'm running Vista RC1 32-bit on is a dual boot with xp pro
32-bit, and when i'm in xp I never have or had this problem, with the same
setup.

However, I have not connected directly to the cable modem, because i'm not
very keen on losing my phone service for long periods of time(Note: As
mentioned earlier, I have VoIP telephone service).

I tried to repair the network connection as well, and this option works
about 90 percent of the time, except the times when the repairing process
freezes.

I think the problem has to do with the network handling in Vista, but who am
I to make a call on this.

I hope one of you experts can help me resolve this problem.

Thanks in advance,
Rocky.