Network consists of 2 pcs linked thru a hub, a printer hung off computer 2, and a cable modem hung off of the hub. The network connection works for both computers without a problem. The problem is that computer 1 has lost the connection to computer 2, and therefore can't print. This connection may resolve itself for a week or two, then disconnects for a while. Network card has been changed out (besides internet works), cable seems to be ok because the connection from pc 1 to hub to cable modem works ok, seems to be a setting, but why does it work sometimes and sometimes not?

r they both windows xp?

no, both Windows ME. In fact, they are essentially twin systems, bought at the same time, running the same software. PC 1 has had problems in the past with viruses, etc. but has been clean for a while.

Write down both computers' IP address when they are working right. Then find out if they have the same IP address when they are not working. They could be swapping IP addresses, depending on which computer you turned on first and second, etc. My computers at home swap IP addresses frequently, and it all depends on which PC was turned on first, in order for the DHCP service on the router to assign it one. This is regardless that I set the IP leases not to expire for 30 days or whatever. Frustrating but I've learned to live with it...

Could it be that they are using a network hub instead of a router. When the connections is working, Computer 2 gets several blue screen errors. Connection hasn't worked in several weeks now.