UNC path is an invalid current directory path. UNC paths are not supported. Defaulting to Windows directory.

From Microsoft: You must make a registry entry to be able to use a UNC path as the current directory.

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

Under the registry path:

HKEY_CURRENT_USER
     Software
        Microsoft
           Command Processor

add the value DisableUNCCheck REG_DWORD and set the value to 0 x 1 (Hex).