Even if you enclose the long path name in quotation marks, Autoexec.nt will NOT process it?
This is by design.
Autoexec.nt is used to facilitate 16-bit programs in the NTVDM and WOW sub-systems.
To workaround this issue, move the file to a path that uses the 8.3 naming convention.
NOTE: You can also check to see if there is a Windows 2000 compliant version of the application.