Why does F4 select my capital?

[SlyFrog]

I am supposed to be able to create unit groups with my F1 through F8 keys. However, for some mysterious reason, the F4 key is stuck on selecting my capital city, even after I try to bind a group to it.

I have checked the bindings in the hotkey options, and it says F4 is bound to nothing. Why is it selecting my capital?

[Jaybe]

I found that the other low F-keys are bound to capitals in general if you haven't assigned them to a group.