Right, cousins networks causing huge annoyances right now.
He has 3 PC's on it, his machine (A), a Laptop (B), and another PC (C).
PC A doesn't see B or C in 'Network Places' but on B and C, A is visible.
From PC A, trying to ping B or C leads to timing out and pinging A from B or C works fine
The router he's using is a NetGear DG834GT if it's any help
Cheers,
David