windows 2000 mapped drive help

My employer has several laptops that employees take home with them. All machines are running windows 2000. I have mapped a network drive on each of these machines that corresponds to a folder on a desktop in our office. The problem I am now experiencing is this: if they start their computer 20 miles from the office, and pull into the parking lot it should be able to see the mapped drive. The laptops lose the mapped drive, but they still can connect to the internet. If I go to My computer I can see the mapped drive, but it has the red x through it. If I go to properties on my network places, then tools/map network drive the drive letter is blank and there is no mapping that I did. I made sure the reconnect button was ticked when setting these up.
On some of the laptops when I go into my network places I can see the -correct workgroup that the desktop is in. But on others I have to do a search to locate the computer by name.
All of these were set up on a wirelss G network, to have internet access in the parking lot and the ability to print from their car onto a printer inside on the network. All worked great until they left the network and returned the next day. Anybody know how to configure windows 2000 so it will automatically find the mapped drive when it is in range of the network???

Or would I just be better off to forget the mapped drive and just share that folder on the network? That is how I did the printer, but it will not print sometimes either..