By default, when you create a shortcut to a network application, both the Drive letter and UNC connection are stored as part of the shortcut.
The reasoning that if the drive letter gets reassigned or deleted, the UNC connection will serve as an additional way to ensure that the application is available.
This can also be a problem because when you want to re-assign the drive to a new server, it will still make the connection to the old one through the UNC

To disable this feature, there is a program called SHORTCUT.EXE in the Admin / Apptools / Envvars directory.
Execute the program with a -? to see a description of the available switches.