PMFJI, I was having the same issues here at the office and at my customer sites. I finally found the solution. Here it goes.

If you go to the network card, properties. In Win2K, right click my computer. Go to properties. Then go to Hardware, device manager. Find network card. Right click and go to properties. Depending on the card type the driver will sometimes have an advanced tab. What you are looking for is a check box that says "Allow computer to turn off this device to save power" or something like that. Basically Windows is shutting off the network card to save power for some reason. I have no idea why, but they wrote the driver to do this. That might solve your problems.

Dale