Problem fixed. Customer is using their HP 1050 HPGL driver, creating a custom size larger than they will ever need, and then selecting that size when printing. In their driver, they check a box that tells the machine to print only the "inked area" and not print blank paper. My IT guy had to change a setting withing the DIMM chip (in the Embedded Print Controller) that would allow the HP driver to be used and to accept the "inked area" box being checked. Prior to this, when we used the driver, the data light would start blinking but nothing would happen. Once we changed the DIMM chip to accept the "inked area" option, everything was fine! Yeah!