F4 key only registering half the time? (on two different keyboards)

I have Win8. For example in TF2 coop. You need to press F4 to ready. At first i thought it was just my new keyboard, so i tried on my other keyboard, that doesn't work also. So i tried a keyboard tester online. All keys register as working except for F4. However, ALT F4 works in closing programs. It has also worked in Tera. I can't for the life of me figure out what is going on. It can't be a hardware problem as both keyboards can't have the same exact problem with F4. any ideas?
one is a wireless logitech keyboard, other is a razer blackwidow keyboard.