The $004E error indicates that GS/OS attempted an invalid access procedure. There was only one way we were able to duplicate this error -- by denying access privileges to the Icons folder on the server. When the access privileges on the Icons folder weren't set to See Folders/See Files for everyone,the "Unable to load descriptors" message appeared. Descriptor refers information stored in files within the Icon folder, which is needed by the Finder. Once we reset the Icon folder privileges so See Folders/See Files were allowed for everyone, startup proceeded normally.
Once access is granted to the Icons folder on the server and Finder is set as the startup application in the server's Admin program, the startup process should continue until you reach the Finder's desktop.
IMPORTANT NOTE: When using the "Icon Info" menu item from the GS/OS "Special" menu, there is one step that is sometimes forgotten. Be sure to press the "Apply" button while on the "Access" card of the "Icon Info" dialog box after making any changes to access privileges. If this button is not pressed, the changes are not recorded and the privileges revert to the previous settings.