1 PC on LAN cannot be pinged by IP address

I have 5 PC behind a router and on the internet. 3 of the PC are wired to a Linksys switch and then plugged into one port of the router.

None of the computers can ping or access MS File shares via IP the address (192.168.1.6) from the same (1) computer which is behind the linksys switch. The (1) computer that doesn't share and will not respond to ping can connect and ping the other 4 by IP Addr and it can also ping itself by the actual IP addr (192.168.1.6).

This has always been a static address for the past 6 years because I used it as a file repository for the other PC's and and my HP scanner dumps scans to it via a Share folder.

I am running Windows XP pro SP3 and the share and ping broke about 18 months ago.

I have made sure the the Windows Firewall is disabled and I have temporarily disable the CA ISS 2009 Firewall. Please remember that the PC's behind the switch cannot ping or share by IP Address to 192.168.1.6 anymore.

Any Ideas?!! Thank You

 

Are all these computer on the same subnet? I.E. .1.x? If you move the computer that is behind the router and put it inline with the machines on the switch, can they communicate?

 

The computer that no longer works is behind the Linksys switch with 2 other computers. All computers are on the same subnet and 4 of the computers communicate and share files with each other in both direction. I am calling it the 5th computer, one of 3 that share a switch which can access all the other shares but no one can access the 5th computers shares any more.

I am now convinced that it has to due with conflicting personal firewall software that was removed long ago but yet is not right. I am chasing down how to remove the Zone Labs "True Vector" service which which should have been removed but wasn't. I disable the service which is no longer used by anything but it still exists.

I hope that this further information can help you help me.

Thanks for your reply.