gigabit networking

I got a linksys gigabit router to link two computers
together: a W98 box, and an XP box. The router is connected
to a hub that's connected to a DSL modem to the internet.
The goal is to have gigabit network access between the X98
and XP boxes for very large (tif) file sharing. (Routing
to the network is not part of the equasion here.)

I have two sets of network adapters: a pair of linksys
gigabit cards, and a pair of netgear gigabit cards. No
matter which configuration I use of these cards to the
gigabit router, the same thing happens:

The XP box works just fine. The W98 box starts ok, but
over time (an hour or so), it begins a series of "stop and
start" behaviors: nothing moves, not the mouse, not the
keyboard, nothing. It'll just freeze for a few moments,
then wake back up and empty the input buffer (mouse
movements, keyboard entry, etc.) and work ok for a few
seconds, only to "freeze" again and repeat the loop.

If you shut down all applications, the computer responds
ok, but the moment an application is started that may want
to see the filesystem (and by extension, the mapped
drives, which require going through the router), the
system freezes and the loop starts again.

Is this a Windows 98 problem? support from the linksys and
netgear people have not yeilded anything.