[jdmccright]

Sounds to me like you're running up against a shortage in current needed to ignite the high beams. The current draw needed by the ballasts is too much so the radio suffers a temporary "brownout" until the HIDs are lit.

Question: does this happen only when you are stopped and at idle or also while driving down the road? I ask because the alternator output at idle is usually much lower than at speed.

Depending on your car/truck, you can do one or two things. 1) Install a higher amperage alternator, or 2) install an inline capacitor to help ignite the headlights and reduce the draw from the car's electrical system. Ask the manufacturer of the HID kit about the availability of this for you application. I'm curious as well since I'm considering a kit for a few of my vehicles.