Printer Driver / Memory clash issue? Help.

Hi - I'm having an issue with a new Lexmark printer and compatibility. I
just installed a new Lexmark x500n printer in our Microsoft workgroup
network. It is intalled as a direct IP port. I have installed the drivers
on each of our 5 client computers. Since then, it seems I have some sort of
conflict between my main business application and the printer drivers. Each
time I try to print from this application I receive an error message
"Omni.exe" (the application executable) has encountered a problem and must
close. The applicaiton terminates and I must launch it again. Several times
after doing this, I could not re-launch the application - I would receive the
same error message. When I delete the Lexmark printer and set things back to
our old HP laser printer, everything works fine. I have deleted and
re-installed the drivers several times, I have downloaded new drivers from
the Lexmark website. All continue to have the same problems. My application
vendor says that the printer drivers are writing to a memory space in use by
the application and there is nothing they can do. I don't have any response
yet from Lexmark. While I realize this isn't directly an XP issue, I thought
I should post for some suggestions on some help. The 3 main computers using
this application have various amounts of RAM (highest is 512k). Two are SP2,
one is still on SP1. Any help would be appreciated as I'm not sure I can
just return a $550 printer for compatibility issues. Thanks -

Michele