Networking File Sharing etc. USED TO WORK before DSL - Please Help

I have 5 computers that share DSL through a Cayman router then to the Linksys router. They used to be able to share files before the DSL was in place. Now I can't get them to share files/printers etc. which I completely need them to do. I have talked with Microsoft which directed me to Dell which directed me to SBC - who we get our DSL from which directed me to Cayman an so on an so on each one not being able to help or not wanting to help. I have done everything I can do. I tried pinging with no luck. Each computer will talk to the Cayman router but not to each other. And then the strange thing is on one of the computers on the network it will periodically see other computers on the network but deny me access to any of them that I see. All computers are Windows XP some Home and others Pro. Please Help!!!!

Does the router have DHCP enabled? If so, check that the computers are configured to obtain an IP address automatically from it. Check that each computer then is able to get an IP address on the same subnet (such as 192.168.1.x). If you can't ping between the computers, disable any firewalls that you have on them, and try pinging again.

Thank you!!! I disabled the firewalls and they talked to each other. But is it safe to have the firewalls disabled?? And also how do I make it so people on the other computers can't get in and mess up my files?? Like password protect them. - But how??

Disabling the firewalls probably is safe, because you're router should provide all the protection you need from the Internet. But, you should be able to re-enable them again if you want. There should be a section in the firewall config where you can add a trusted zone, by adding the IP addresses of your other computers. Once you've done this, you should be able to use the firewall and communicate between the computers.

If you don't want other people to be able to view your files, then remove the share on that folder. There should also be an option in the Sharing tab, where you can allow people to view the files, but not change them.

If you want to password protect your folders, disable the guest account. Create a new account with the username/password that you want, then when someone trys to access the computer, since the guest account is disabled, they should be prompted for a username/password. Use the new account details to continue, and you should have access to your files.

You could also encrypt any of the files you don't want anyone else to see. Use sharing and security for added security.

thank you for all your help. everything is working!!!