Panasonic KX-P2130 Custom Paper Setup

I currently have 6 machines running Win98 & 1 machine
running MinME. Everything running ok. But as hardware
fails we are slowly upgrading to newer pc's. All of which
have the XP Pro with all the latest updates. But we are
having a conflict with the Custom paper size setting. We
use a special 8.5" x 8.5" fanfold with a .250 left & .250
right margin. As soon as we set this in XP we keep
getting a page mismatch warning. We have even tried to
reset our custom form in the Alpha5 ver 4.03 build 230
program to accomodate the error message but it will not
print correctly, it cuts off the data. As well as prints
a background of dots across the form. Any suggestions or
ideas? We have contacted the software developers of Alpha
& they have been of little help. I have also talked with
a consultant who has been slow in responding even when
asked to come in to check out. So far nothing has
worked. As older systems fail we are now down to only 3
machines that can generate invoices. HELP PLZ