This sounds potentially like a Reports.dic issue. Do you know if there were any errors when your modified reports were upgraded (hopefully they were upgraded). Are you using the modified version of that report?
You can check by going to Administration >> Setup >> System >> Alternate/Modified Forms and Reports, choose the ID that is assigned to your user (found in User Security), choose the type as Reports and Series as Financial. Is there anything listed in there for GL Detail Inquiry? If so, try switching it to the unmodified version and printing.