I just installed a new ceiling fan in my kids room earlier today. There are two switches on the wall. I started the day with a dimmer switch and a regular switch. Once everything was installed I turned the power back on and the fan worked, but as soon as I turned on the light (on the dimmer switch) the fan would start making a humming noise and would start slowing down.
I couldn't get it to work right so I thought maybe the dimmer switch was the issue. I had a regular switch laying around so I swapped it out for the dimmer so now I have two regular single pole switches. I turn on the fan at the switch, works like a charm. I then turn on the light (at the newly installed regular switch) and the light turns on BUT the fan turns off! No humming any more from the motor, but it just turns off. As soon as I turn the light back off the fan turns back on.