I have the same basic problem, but with a few differences. Our workstations are all XP Pro or XP Home, so Win98, 2000 Server, and AD would seem to have nothing to do with it. The disconnected drives happen occasionally throughout the day. One can be running a long job such as a backup, with Windows Explorer open at the same time, and an hour or two into it, WE suddenly shows all the links as disconnected. Just run the mouse over them, they connect back. A couple hours later, they're back to disconnected. Various programs seem to fail with access violations when shares they try to use are in that semi-disconnected state. Driving us nuts...

net use /persistent:yes is default settings for NT and win2000/XP. This is why when you have mapped some network drives and check the reconnect at logon, or your network uses logon script to map network drives, the mapped network drives may show red Xs after rebooting. If you enable echo and pause the logon script or if using net use to map the same drive manually, you may get "System error 85 has occurred. The local device name is already in use." One thing you may want to try to avoid the red X is using net use /persistent:no, for example, net use i: \\servername\folder /persistent:no