>I have the serial console permanently connected to my COM PC port and I
>Access the console using Hyper terminal from Windows. The problem is
>that if I reboot my PC leaving the serial console cable connected after a
>while also the VAXstation crashes (4000/60), I have NetBSD 1.5_BETA2,
>and when I go to see the console there is the PROM prompt

This is a feature. Whenever a VAXstation is in alternate
console mode (which I presume yours is) it interprets a 
set number of SPACE characters as a BREAK 
(space as in mark/space ... not the space key on 
the keyboard). When it sees a BREAK it drops into
console mode.

I don't think there is any way of disabling this.

When it happens you can just CONTINUE from the console
prompt and all will (probably) be well.

Antonio