We've been trying out LED bulbs around different places in the house. Two Home Depot dimmable PAR30s worked great in a four-light-bulb fixture in the kitchen. I added a dimmable Philips BR30 bulb, and suddenly the dimmer doesn't work (on any of the LEDs - it works fine on the one remaining incandescent flood), and the two PAR30s dim suddenly, one at a time, without warning or anyone touching the light switch.
I don't have another dimmable fixture that I could try out the Philips to see if it's a dud. The bulb gives out light, in this fixture and in another.
What do you think my next trouble-shooting step should be?