Brother 2460 printer

I have a Brother 2460 with 2 paper trays set up in three small branch offices. one tray prints production documents, the other tray prints checks. The printer is networked and DHCP is active. Windows 2003 Server is providing DHCP Service. The print jobs are set up through printer preferences. My problem is the printer preferences are not stable and change with time and/ or during print jobs. Work stations are running WinXP Pro. Any suggestions on how to correct this problem?