Ping and some Remote Administration functions don’t work in Win XP SP2

We noticed that about 95% of our desktop units on the floor are not pingable. At the same time we noticed that we cannot utilize certain remote functions such as RDP. Since we generally utilize PC Anywhere for remote support it hasn’t been an issue. However, we’re now looking at new software that is affected by this. We’ve checked some machines to make sure that Simple TCP/IP Services are started, Remote Administration is turned on, NetBIOS is enabled and File and Printer Sharing Services are installed. Any suggestions? Thanks.