marky3d, the issue is also quality of suck el-cheapo products.
As I said, I heard also lots of problems from people who bought it in my country.
From lots of light flicker, to bulbs burning out, and similar intermittent problems you have.
Basically, it's one of two things: poor wiring, or poor product itself.
One of dangers people forget is using those aftermarket kits, and just replacing their regular 10A fuse with 15 or 20A fuse, and using same wiring.
Unlike halogen light, which is rated 55W, and thus draws around 4A,
HID's on powerup draw ~12A each, which stabilizes at some 3A after some seconds (35W).