wterm and keyboard

I have two computers sharing one keyboard through switcher.
Both computers are running under QNX 4.24 with QNX Windows
from April 1996. When I have launched Shell
(/windows/bin/wterm -c /bin/ksh)
sometimes when switcher changes position,
the console gets stuck, it does not react on keyboard.
Newly opened consoles work fine. When windows go to sleep
mode and back, also the freezed console works fine.

Had somebody similiar problem ?
Can you give me advice how to solve it ?

Thanks, Andy