I never used QNX4 but I did use QNX2 quite a bit back in the mists of time. The message on the screen seems to be about a file that does not exists somewhere in /user/script/?????_50.
QNX2 is a multitasking operating system and may run different tasks on different consoles. From memory, you press Ctrl, Alt + 1,2,3 or 4 to switch between consoles 1,2,3 and 4 for example. I seem to remember that QNX4 is Xwindow compatible so it may behave very differently. There may be other consoles mounted and or running other tasks but it seems not the comms task.
Scratching the grey matter some more, QNX2 ran a script file on startup called sys.init (maybe sys.init.0). It looks like part of the startup script is looking for a file that now longer exists; maybe a recipe data file. Could it be that the current working recipe has been deleted?
Nick