Last night I decided to do some detective work. So, when it happened, I just left it along and went through the house turning on lights and things. Several lights, I'm assuming they are on the same circuit, were very dim. (we use those curly cue florescent bulbs). Nothing I did changed the fan speed. This morning I turned the fan on and it ran fine. I'm wondering if a breaker could overheat and drag the power down. Also, we have a terrific infestion of fire ants and those damn crazy rosemary ants (I think that's the name---it's a new discovery here in south Texas and they are taking over everything so fast it's unbelievable) But, I've dealt with the ant problem before and this just doesn't act the same.
I'll be calling the local electrician but before I sprang for that 100 bucks up front, I thought I'd check and see if anyone else has had this problem and might have an idea what's going on.