Simple Lan looses mapped drive on xp computer

My business has a simple lan with a computer with win2000 pro as the server and about 4 other computers connected. All need acess to the mapped I drive for a specific program. One user (the only one with win xp) keeps losing the ablility to connect to the mapped drive. I have checked her user configuration on the server and it is fine and everytime I check it it works but she says one day it works and the next it won’t. Any ideas?