Firex is a thing of the past around here. I don't know a single contractor that still uses them. I believe they had a HUGE recall on thier smoke detectors not too long ago too. We use BRK's now and they work nice with very little annoyances and call-backs.
As far as the reason why bulbs and smokes are both going out, I would do a voltage test at the mains first, than try changing the leg the circuit is on. Are the smokes and bulbs on same ckt?
