When using the PCL mode, if a small document (less than one page) is sent to the printer and it doesn't fill the buffer, or the program doesn't send the proper end-of-file, the job sits in the printer buffer. It stays in the buffer until an end-of-file is sent or until something causes the printer to flush the buffer - such as shutting off the computer. This could be the problem since it is very common MS-DOS computers. Most MS-DOS based printers, such as Hewlett-Packard printers, have a front panel form-feed button that you can press to flush the buffer. This clears the buffer, but you still a blank page.
Another possibility is a bad cable. If the pinouts are off, or the cable continuity is marginal, you get symptoms like you described.
Workaround
First try a different cable. If that doesn't take care of the problem, then the application isn't sending an end-of-file or the buffer isn't getting full on the last print job. If the problem is due to the print buffer, then there is nothing you can do other than to turn off the printer, or get the blank pages.