Networking woes with 98SE and XP

We have a 25 computer network with 2 servers, one an NT 4 SP6 running Exchange and another a Win 2K SP2 as our file and print server plus HIS 2000.

They are in different domains but they communicate without a problem. Some of the clients however,are not as fortunate. On 2 of the W98SE PCs we repeatedly lose network connections (i.e. mapped drives) and upon reboot, we get them reestablished.

On the new XP machine the problem is worse since we repeated lose the mapped drives, and also thenetwork printers. I have no idea why this continues to happen. It does not occur on the 2000 machines which make up most of our network.

Any ideas what could be happening?