You could create a method to convert the Drive letter to UNC


LPARAMETER cDriveLetterToCheck
Local cBuffer, nResult


Declare Integer WNetGetConnection In Win32API ;
String @cLocalDrive, ;
String @cRemoteUNCBuffer, ;
Integer @nSizeOfBuffer
cBuffer = Space(511)
nResult = WNetGetConnection(Left(cDriveLetterToCheck,2), @cBuffer, 511)

nResult is the UNC value of the Mapped drive.
You may want to do some checking for if the Drive letter is a local drive.