Sexi2k

More than likely it's the ballast. Had the same issue on another car with HID and had the same issue. The headlight would even go as far as turning off and randomly turning on again. Took bumper off and saw ballast hanging (ziptie before) and putting tension on the wiring but the ballast was on its way out from being knocked around while hanging.

Hfreak

^^^ X2, swap your ballasts from side to side to confirm. Mine was very similar but would also shut completely off.