PC's losing the network ???

Have just set up a 9 PC network. 8 on wireless and 1 connected directly to
the wireless router.

Everything was working fine, all pc's appeared in network neighbourhood,
could share files/printers.

I set up a mapped drive on each of the wireless machines (n:\) to point at a
directory on the wired machine, all went well.

It worked for about a week, then 2 wireless machines decided they could only
see each other and no-one else. They could not be accessed from any other
wireless machine either, however if you searched for the machine name on the
wired pc you could access the files/printers etc.

Rebooted both pc's and one appeared back on the network however the other is
still in the same state. and another 2 pc's have now decided they cannot see
the network or ANY other pc on the network. You can however access the pc's
from the wired pc in all cases.

The wired PC is runnin win98se and the wireless pc's are running win98se,
win me, winxp home.

This is driving me nuts. Can anyone help ????