Losing mapped drives

I have a client with Windows2000 Professional acting as a peer-to-peer “file server”, with Windows 98 clients. The Windows 98 clients keep dropping their drive mappings to the shares on the Win2K box. Sometimes 2 of their 3 mapped drives are OK andcan access the Windows 2000 machine, but the third drive mapping is lost and has to be remapped. Does anyone know why this could be happening or how to fix it? Might it have something to do with the BrowseMaster registry setting? In addition,and separate from the dropped drives issue, the Windows2000 machine has frozen up a couple of times, which also prevents users from connecting. Are these 2 separate problems or do they stem from the same source? Help!