I'd go ahead and spend the money on a replacement bulb, and give that a shot first. I'm sure it didn't burn out from use, but it may have been a defective bulb. If the new bulb does the same thing, I'd start looking into any warranty that you might have with the ballast. I don't know much about HTG, but many HID manufacturers warranty their products for at least some period of time. If it's defective, hopefully you'll be able to get it replaced. If your electronically inclined, you could open it up and check the leads and wire connections yourself... BUT, this would probably void any warranty it may have if you make it obvious that you tampered with it.