I had to go through the unfortunate procedure of having to reset my
router settings to factory defaults and configuring a network where
everything was pre-setup 2 years ago. Anyways, I got the
configuration settings all working ok, so that my email server and the
computers on my internal network are working.

Here is the problem: I have an ADSL connection, which is connected to
my Router. The router than has connections to a switch, where all my
other computers on the LAN are connected. I routinely get this
problem where one or the other computer on the LAN loses its
connection to the internet. It is still functioning absolutely ok on
the LAN, but just does not connect to the internet. The other
computers on the network which are still functioning absolutely ok, as
in, they are connecting to the Internet with no problems. Sometimes,
after a few minutes, the internet connection works again, and
sometimes, the computer has to be restarted in order for the internet
to work on it. This is all spontaneous and I could not figure out why
this is happening. I would really appreciate any help.

PS: All the computers are Windows-based: Windows NT, Windows ME and
Windows 98 machines on the network.