2 Win 98's and 2 Xps

I have a 98/98/XP/XP/router setup in which

-All machines can access the internet
-All XP machines can see everyones files
-One 98 machine can see everyones files BUT
-The other 98 cannot ( ie hourglass hangs there when I hit Network
Neighborhood ; cannot ping )

Is there something simple I am missing?

None of the machine are using NETBEUI, or static IPs or LMHOST files

Marvin