are you useing an OS other then windows 2000 or vista? from what i've experienced, 98, xp, and me are complete crap when it comes to accessing other computers via My Network Places
i've never had any trouble getting a win2k pc to access any other pc i had. be it 98, 2k, me, xp, or vista. no problems at all.
but when it comes to xp, i was rarely able to get one xp pc to access the other xp pc or the win2k pc. many times the other computers just woulden't show up. when they did show up, usually it'd just say it coulden't locate the other pc on the network, other times it would just say that the network wasen't available or that it coulden't log into the network. even though the network was working fine enough for the 2k pc to access the xp pcs
as for win98, i remember having the exact same problems as with xp
so far my vista pc is having absolutly no trouble accessing my XP or win2k pc over the network via My Network Places.