Hi Naomi:

I always use Alt+f4 to close my applications and it works everytime except when I'm using my keyboard at home, which is a logitech keyboard that I think remaps what the "F" keys do. I can set it up differently so it has the traditional usage, but if it ever goes back to it's own way it throws me for a loop and at least for a bit of time after pressing the F keys, I'm wondering what happened.

I wish I could provide more help but this has just been my experience.

Paul