2 pc's suddenly not communicating

I have 2 desktop pc's running xp sp2. They each have a D partition on internal hard drives that are shared and mapped as Z drive on the other pc. They are shared through a linksys router and the internet works fine on both, none are wireless. For the last year this has been fine. Now suddenly these pc's are not communicating. Nothing has changed and no windows updates have been done. I have windows firewall disabled as well as the firewall in the router. They both have zonealarm and avg and since this issue I have disabled them. Here are some things I have confirmed and have tried:

*Both on same workgroup but I have renamed it. I gave them new computer names too.
*Both are using the administrator account with same username and password.
*On both, I removed then reinstalled "Client for Microsoft Networks ", File and print sharing for Microsoft Networks ", and NetBEUI with a million reboots of course.
*They cannot ping each other, their ip's are 192.168.1.100 and 192.168.1.101.
*The sharing is sill enabled on the D drives and the printer.

 

First, I'd recommend you turn on the firewall at the router. I very much doubt that is the problem, and you need to be running a firewall.

If you have correctly functioning internet on both PCs, both have compatible IP addresses and they cannot ping, I think you have to be looking at a firewall/anti-virus issue.

I'd recommend you disconnect the router from the internet. Then un-install both the anti-virus and firewall from both PCs. Then test again. If networking then starts working, reinstall both av and firewall and try again.

Once you've finished testing reinstall anti-virus and firewall, reconnect the router and post your results here and we'll move on from there.

 

Ok I just figured the problem. The 2 pc's have ip's of 192.168.1.100 and 192.168.1.101. I had to go into Zonealarm settings and add the other machines ip to the "zones" list and make it trusted. In other words .100 needed to have .101 added as a trusted zone and .101 needed to have .100 added as a trusted zone. I have been using zonealarm for years and never had to do this before. Oh well, Thanks for the help everyone.

 

Most personal firewalls will let you "trust" a range of addresses. As you are using a private address range (192.168.1.0/24), you can safely trust that whole subnet. So trusting 192.168.1.* or 192.168.1.0/24 or 192.168.1.0/255.255.255.0 or 192.168.1.1-255 will be a safe option that will carry on working if your IPs change to one of the other addresses in the range or if you add a third PC.