SBS 2003 Cannot see all Client Computers through My Network Places

I have a SBS 2003 Network with about 15 Clients running Windows 200 and XP Pro. I have added 4 new client machines, XP Pro, to the network using the connect computer wizard. I am unable to view these PCs through My Network Places. NetBIOS is enabled and I have static IPs which I can Ping via host name and IP. I have not been able to find any helpful info online. Also all services are running correctly, Computer Browser, WINS…

Thanks!

P.S. – Another one of my clients is having the same problem. I can only see 2 PCs of the 10 in the network through My Network Places. I wonder if there was an update that did something?