Dual Monitors and DOS problem

Our employer has Win98SE installed on our PCs with a Nvidia Geforce 2MX 400 TwinView Plus video card. I need to be able to view a DOS database on one monitor and a Windows program on the other at the same time. However, if I attempt to view the DOS database in full screen mode rather than a window, the other monitor goes to “black”. If I exit out of the DOS program, the other monitor’s display returns to view! I need to view the DOS program in full screen rather than in a window. Otherwise, I loose some functionality. EVGA, who makes the TwinView card, doesn’t seem to have an answer to my dilemma. Is the problem one of hardware, OS, or DOS? I’m stuck with the DOS program for a couple of reasons beyond my control.