map drives

I created a folder on my Windows 2000 Server. Then, I shared the folder and gave eveyone FULL CONTROL of it. I went to each individual workstation and created a MAP DRIVE to that folder(\\servername\foldername). The next day, I click the icon “My Computer”(Desktop) and tried to access the drive. There was a red x over it and when i tried to click on it , i got the message, “Could not reconnect , file name already in use”. I then disconnect the drive and remapped it. Why do u think this is happening?