PROBLEM PRINTING CUSTOM SIZE IN WINDOWS XP PRO

I HAVE A PANASONIC KX-P1180 DOT MATRIX PRINTER. I PERFORMED THE ROUTINE I READ HERE TO SET UP A CUSTOM PAPER SIZE SO THAT MY LABEL PROGRAM WOULD ADVANCE ONE LABEL AT A TIME. PRIOR TO THAT, IT WOULD PRINT THE LABEL FINE BUT THEN ADVANCE SEVERAL LABELS. AFTER I SET THE CUSTOM PAPER SIZE OF 3.5 IN WIDE BY 1.0 IN HIGH, IT PRINTS A FEW UNRELATED CHARACTERS ON ONE LABEL, THEN ADVANCES SEVERAL LABELS AND DOES THE SAME THING. I CHECKED THE PANASONIC WEBSITE AND FOUND THAT WINDOWS XP HAS THE CURRENT DRIVER FOR THE PRINTER WHICH IS THE DRIVER CURRENTLY INSTALLED. PLEASE TELL ME WHY THE CUSTOME PAPER SIZE IS CAUSING ERRATIC PRINTING.......THANK YOU....JOHN