ICS stops working every few days

Hi,

I hit a strange problem and despite some effort could not fine the answer in
any of the newsgroups or on the net.

We have a peer to peer network with a number of Win98 and WinXP computers,
one of them is using a dial up internet connection which is shared, so
others can access the internet. I use static IP addresses on all systems.
(192.168.0.1 for the internet gateway computer). Everything has been working
fine for a long time. But now every few days users on the network cannot
access the internet any more, the gateway computer has still access to the
internet though, and the rest of the network is fine too. So after trying to
fix it some other way I deleted the shared dial-up internet connection and
recreated it and it worked again for a couple of days until the same thing
happens again and again and again.

The system is virus free and disabling the NIS and XP firewalls (for
testing) do not seem to make a difference.

To fix like that only takes a few minutes but it is like having a small
puncture in your car tyre and you have to keep pumping it up, usually when
you are in a hurry.

Any ideas?

--
Meini