wired home network problem

I have a wired home network using internet connection sharing. (I'm stuck with dial-up) My internet gateway uses XP home. Have 5 other computers sharing the internet connection, file and printer sharing. All the other pc's use XP pro except for one linux machine. I have 2 linksys ezx55w workgroup switches. Everything has been fine until the end of July, one of the XP pro machines suddenly would not connect to the internet, printer, or access files on the other machines. Network connections show it's connected to the lan at 100 Mbps. All lights on the workgroup switches are on, green light is on on the back of the pc where the ethernet cable plugs in. Was going to re-install Windows, but today another XP pro machine started having the same problem. I have the IP addresses configured manually, if I use automatic IP addressing, I have limited or no connectivity. Could I have a bad workgroup switch even though the machines show they are connected at 100 Mbps ? Not sure what to do at this piont. Any help would be appreciated.

ipconfig in cmd =)

Check out this link for some help on trouble shooting your connection,give the Ping test a try -

http://www.onecomputerguy.com/networking/troubleshoot_internet.htm