HID headlights malfunction

Well, I did a search and came up empty, so I'm hoping someone here can help with my problem.
About a month ago I noticed my HID headlights start to flicker and eventually turn off. Luckily only one lamp goes out at a time, so I've been able to drive at night. Funny thing is that this doesn't happen all the time, only occasionally. I think the bulbs are fine and suspect that it's a regulator or sensor that is malfunctioning.

Anyway, I decided to post here to see if I could save myself a trip to dealer. I'd hate to sit there for hours or leave the car overnight. Does anyone have some advice about a possible solution to this?

Tuco