malfunctioning Uv/Heat bulb

Question
I purchased an Exo Terra Solar-Glo High Intensity Self-Ballasted Uv/Heat Mercury Vapor Lamp for my desert tortoise's time indoors. I am using it with a large open cardboard box. I have tried two different clamp on heat light bases and the bulb still malfunctions most of the time, when I first plug it in. It will blink and not stop blinking. So then I unscrew and re-screw it (sometimes several times before it will work) and eventually it will just blink ever so slightly but will stay on. Any ideas?

Answer
Are the bases you're using rated for the wattage of the bulb?  Also, those bulbs get hot, heat and cardboard worries me a bit...  If the bases are rated to handle the wattage, I'd contact either the store you bought it from or Exo Terra for a replacement.