IP Problems on WindowsME??

Hi all

I visited a client today with a network of 4 PCs configured as
follows:

1st PC:
PC with internet gateway running WindowsXP Pro and fixed IP
192.168.0.1

2nd PC:
A SERVER PC running windows 98SE and fixed IP 192.168.0.2

3rd PC:
Running WindowsXP Home and fixed IP 192.168.0.3

4th PC:
Running WindowsME and dynamic IP 192.168.0.84

All PCs used the DSL internet connection of the 1st PC.
All PCs were able to access each other and use any shares setup.
All PCs connected by CAT5 to a 5 port hub
The 1st PC's internet connection was via an attached USB broadband
modem

The system was working just fine until my visit today!!!

My brief was to install a new DSLModem/Wireless/Router and add a new
notebook PC to the LAN wirelessly and enable internet connection to
it.

I removed the old hub and USB modem from the 1st PC. I then
reconfigured the Network cards of 1st, 2nd & 3rd PCs to obtain their
IP addresses dynamically from the new router.

I installed the new 3Com DSLModem/Wireless/Router using it's default
IP 192.168.1.1. In short, PCs 1, 2 & 3 were returned to full
functionality enjoying the internet connection and shares etc etc.

I then restarted the 4th PC expecting it to have a new IP in the
192.168.1.* range. After restarting I used the IPCONFIG command from a
DOS window which showed the IP address to be the old 192.168.0.84. I
tried to PING the router at 192.168.1.1 and it failed!

I restarted the PC again but still it had the IP address 192.168.0.1.
Pinging the router again failed! I then fixed the IP address at
192.168.1.84, restarted the PC and this time I was able to PING the
router however. I could not get an internet connection.

I treid setting the Gateway to 192.168.1.1, restarted the PC but still
no internet connection.

So guys, it's over to you as I'm stuck!!

1. Why wouldn't the PC obtain it's IP dynamically from the router as
all the others hadn't?

2. How the heck can this PC get access to the net through the router
as the other PCs do?

I do recall in the dim and distant past having to edit one or more of
the .ini files, but I'm not sure!

Regards

John