Here is a situation that occurred using an AT6400 card on a Windows NT 4.0 machine. The NT computer was in administrative mode and had the winrt.sys file in the right place, but Motion Arch 3.32 would not open the terminal. Changing the address and also the slot that the card was plugged into did not fix the problem.
The winrt.sys file is not just for our products and we found that this computer had a few devices that also used winrt.sys, like a video grabber and a digital I/O card. One of these devices was set as device 0 for WinRT and that was where the conflict was. Even though these devices were no longer present, the registry still thought device 0 belonged to the other device. We changed the device number of the other cards and let the AT6400 card be device 0 and the problem was fixed.