Dropping connection

Anybody got any clues on this one?
I have a home network with three pcs connected to a wired Netgear router
(192.168.0.x). My cable Modem connects to this router at the "internet"
port. I also have a wireless/wired Linksys router (192.168.1.x)
connected to the Netgear from one of its ports to one of the Netgear
ports. This is so I can wirless connect to the network with a laptop and
handheld. All the computers are set to obtain their IP automatically.
The laptop occasionally tries to connect as 192.168.1.x and I have to
reset it so it reconnects at 192.168.0.x and can then access the network
and internet. I know this is because I should really only use the
Linksys and not confuse things with two different IP addresse ranges,
but it generally works well.
This is the main puzzle. Every now and then my office pc (Windows XP)
loses internet connection (totally). If I simply unplug the network
cable that connects it to the Netgear router and plug it into another
spare port it immediately connects again. This new port is the one that
lost the connection the last time (there is one spare port on the Netgear).
Is there a reason this is happening and a way to fix it?

Pete