Does anyone know when the F2 save game 'kicks in'? So far it is totally unresponsive although I have just started playing - just past the practise room. I need to fix this because I know the game gets tricky later on.
I am running xp on Mac Bootcamp which shouldn't be a problem.

r u passed from 1° nuclear door? =)

Its a bit confusing, what you actually have to do is press F2 to make a save file and then press enter to save the game at your current spot. Then when you want to load it either do so from the main menu or press F3 in game and select it. As far as I know there's no autosave or anything of the sort so you have to just remember to keep saving. I think/hope that answers it.

I have the same problem. I can't save the game, and I've gone pretty far.

I think this was covered somewhere before... you have to press Fn+F2 on a Macbook because the keys are already mapped to something else, IIRC.