Somethings to check on and think about while you are waiting for TAC: Are the AP's connected directly to the wireless switch or do they pass through other network switches? Do the AP use power injectors? If you have a chance you might check for power related issues with a DMM. Did the new Cisco AP use POE or an injector for power? If it is getting its power a different way then you might find a culprit(low voltage, surges, bad battery backup units). These are just somethings that can be ruled out quickly but can ruin your day.