If you place a mapped drive first, in the path of a Terminal Server, there will be severe connection and access problems.

If you where to ammend the PATH, as in S:\Folder1\[\Folder2\];%PATH%, in either Control Panel / System / Environment or in the Autoexec.bat, or in any way make a mapped drive the first element in the PATH, you will experience strange access and connection behavior.

You may place a mapped drive in the PATH, but it can not be the first element.