Help configuring Windows XP (running into connectivity issues)

hi,
trying to set up a simple windows workgroup environment to share files. Here are details:
– 4 PCs (XP)
– RJ45 cables to a 4-port switch
– NO INTERNET ACCESS (LAN only)
– PCs configured using 10.0.0.x (1-4) static IPs
– Windows firewall disabled

PROBLEM: right now i have “stable” connectivity between 2 of the 4 computers. third cannot ping to other PCs at all. fourth one pings 50% of the time.
rewired network multiple times – so pretty sure wiring is not an issue.
help!