network enigma

You are experiencing a nic driver problem on those machines, due to the fact that the nics are working, the machines are working but without a network, cables & hub is working, etc.
Previous a nic uninstall, check first if your nic driver has a speed configuration, that place where you can change the speed of the card. If you have it, turn into the lowest value.
What protocols are you running? If running only tcp/ip and your dhcp server is unable (for some reason) to deliver an ip address to your machine, networking will remain disable.
If still not working, go to network panel, and delete the card. Boot and start all over again, but be sure to load the drivers from the cd or diskette. Do not let windows use the driver currently installed, thus it may be damaged or be invalid.

Hope it helps.!!

First, see if you can ping other machines ( servers and client ). If you can ping by name and it resolves then it's a protocol problem. If you can ping by address only then the network configurations have changed. If you can't ping at all then the problem is physical.

Not having all the details I will presume that even though you get this error at initial boot up you have the problem go away after a while and you are able to access the network okay. Normally when the PC's are turned on they have to negotiate speed and flow settings with the switch that they are connected to and after this is complete they are bale to access the network fine. the problem is that sometimes the PC's boot up before the negotiation is complete and you get the "Network not available" message.
One way you can get around this if you are using Cisco switches is to turn on "Portfast" for the ports that these PC's are connected to. This basically turns off negotiation for these ports. will watch this thread for more updates.

Another possible cause of the problem is a missing domain\workgroup browse master. Assuming the rest of machine are NT based they will use a designated (automatic) server as a browse master but if there has been a change in server roles for some reason or if something forced an election between N.I.C.'s then the win9x machines will not have adjusted to the new role and there will be no list of browseable m\c's. Check the browse master setting (Client for MS networks)in the network control panelon the 9x boxes. If you set this to automatic then each machine should negotiate with each other (in theory) which one (or all) which will be browse master.

Have you enable WINS on that client? Enabling WINS help the client to find DC.

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