Agreed. Choose channel 1 for the first AP and 6 (or 11) for the second. Your problem will most likely be solved.

Do not use a 40Mhz channel, because that uses channel overlapping and isn't "neighbour friendly" at all. 40Mhz is also less stable and even if it provides you extra speed (which is not guaranteed) in 99% of the cases you won't need it. (if all you're using your wifi for is internet surfing, like most people. )