Maybe I can add some info.
I have been first at the very lowest wooden door and switched on power first. Than go back to the Venti and turned on the power.
Is this “bad behaviour”? What did we both do wrong, so our black mesa crashes?
I don’t want to start all over and stop there again.
Is anybody out there, who can tell us a solution?
[EDIT 1]
Now I found out something new: I started at somepoint before I have to climb down all the levels at the Rocketlouncher and went directly through the upper door normaly locked by woods. Now I can go to the venti and turn it on and wait till it reaches full power. No crash.
[EDIT 2]
Ok, this is how it goes: Go back to a savepoint before you powered up the generator (with Smithers). If you start the generator before the ventilator, the game will crash if the Ventialtor reaches maximum.
This is a Bug!!! Please fix it somehow.
Best regards and thanks
JamFX