Pulsing and Constant light from 3-way switch?

We have two hallway lights controlled by two separate light switches (3 way switch). One switch has a dimmer, the other does not.

When we turn on the hallway light, with the dimmer at its lowest level, half the time both lights are on at the lowest levels of brightness (constant) and the other half of the time the lights transfer, turning on one at a time (pulsing). The probability that the light is either constant or pulsing is approximately random (50 percent)

Any idea as to why this effect is occurring?