I'm having trouble figuring out an issue that's showing up in two exterior and one interior light socket.

In the upstairs laundry room, you turn the light on, the compact fluorescent bulb lights up, and 5-60 seconds later, it dims noticeably. Fan running in that room does not change speed or noise.

Front porch light turns on, then shuts off 1-5 minutes later. Bulbs last a few weeks at most. Same problem in the back yard, light goes out and it eats bulbs.

Rest of the house is pretty reliable, but these three sockets are always issues. I suspect they're not on the same circuits - the physical layout makes that unlikely but not impossible.

I'm guessing it's not the switches or the sockets themselves, but I'm not a professional. Does anyone have a guess as to why this might be happening and what I can do?