...but what's causing this problem? This is happening on various PC's on our network at work. All the PCs are running Win98 2nd Ed. It started a few months ago. At first after signing in with Client for Microsoft Networks, network resources would not be available, such as access to our internal e-mail server, proxy server access, network drives, etc. This was affecting numerous users and would happen multiple times to each user but at varying times. It wouldn't happen to everyone at once, but more often two or three people a week. After running winipcfg, we found out that the subnet mask (which is supposed to be 255.255.255.0) was reverting to 255.255.0.0 or 255.0.0.0, killing network access. Now, some pc's won't even hit the log in server. Once you type in the password it says "Network could not validate your user name..." as if it was unplugged from the network totally. We've been able to "fix" these PC's by going into safe mode, changing primary network logon to Windows Logon and disabling log on to NT domain, restarting into "normal" mode, running winipcfg, release all and renew all, reset the logon to Client for Microsoft Networks and checking logon to NT domain, restart and then the user can log in again. Has anyone had any experience with this type of problem before and what might the solution be? Thanks in advance.

Just a guess, but maybe it's a DHCP scope/router issue? DHCP clients use a broadcast packet to find a DHCP server, so if a client is on one side of a router, and the server on the other, it is possible the router will filter out those broadcasts. Avoid the addresses used by the router, and the non- DHCP hosts. I don't even know if you've got routed segents on your network - just a thought.