Get an electrician in pronto! If your power is being interrupted only on certain circuits and then it comes back on later your having a grounding out issue. I had this problem in an old house and what was found that at one point I had a squirrel in my attic that chewed through the wire insulation, leaving all three wires exposed in a 2 inch space. When a load was placed on the circuit the wires would heat up and bend a little and make contact. That would power down the circuit. After a while when the wires cooled down they would break the contact and the circuit would be active. No load and everything was fine. What I thought was interesting that never once did it blow a circuit breaker. Quite the fire hazard. The fiberglass insulation was where the wire was laying so that prevented a fire. Had to have that line replace and all was well. Mice, rats squirrels can do a lot of hidden damage. So back to my original statement, get a qualified electrician in and have him go through your attic now, not later. You and your families life are in jeopardy right now. Make sure your smoke detectors are working. This is not a joke my friend or a wait and see if something else happens, this is your home and family and no screwing around. Do it today.
Jon
Jon