1988 called, and they wonder why you never visit
This might be a real tough one to diagnose.
Are you booting into DOS on these computers, using DOSBOX or another virtual machine, or attempting to run AI-2 natively in Windows ?
This might be an operating system configuration issue, a driver configuration issue, or a hardware issue.
Are you using the old ICOM 'Smart Cable', a 1784-PCMK with -PCM2 cable, or some other hardware interface ?
We could use some more PLC-2 expertise around here; most of our knowledge is getting stale. Thanks for posting !