I bought this today and I really was angry when the game refused to let me rebind my arrow keys and several others (end, insert, pageup ...) just because those are used in for emenus and the game had them reserved.

However there is an easy workaround which at least worked fine for me. Go into key rebinding options and turn off your num lock. Then rebind the keys using the numpad keys (meaning 8 would be up arrow, 2 arrow down ect. - you can also use those end, pageup ect. keys). Save the values and turn back num lock if you like. Now you have reassigned the regular arrow keys and the keys above the arrow keys (pageup, end ...) as well.