Hi:
I have a rather mysterious problem. I live in a condo building. For a while I had noticed my bedroom & bathroom lights occasionally flicker a little bit, but I didn't think much of it. Yesterday morning my lights went completely out in the bedroom and bathroom, as well as the refrigerator in the kitchen (which is not next to the bedroom), but remained on in the rest of the house. I checked the breakers thinking that might be the problem, but all of them were in the ON position. I did turn all of them off and back on just in case. This did not help. The bedroom, bathroom and refrigerator are not on the same breaker. The lights came back on after about 15 minutes. But, the same thing happened again today. This time, the same light were off for several hours before returning.
Any idea what could cause such a problem?
Thanks so much!

Sounds like a very similar problem I answered here:

https://www.askmehelpdesk.com/electrical-lighting/losing-partial-power-house-72277.html

Simply because of the multiple circuits, and circuits that I would not expect to find a shared neutral being used.

Is it at all possible that your circuits are controlled by a circuit breaker in someone else's unit? You might check to be sure your breakers actually control the circuits at issue.