I had the same problem when the ballast went. Could also be the igniter behind the bulb, but the ballast is most likely. Took me an hour to swap on the passenger side, headlight didn't have to come out.
They're not that expensive. I think this is it?
http://www.ebay.co.uk/itm/NEW-Hella-...wAAOSwI-BWHqI2
edit: sorry that one is for D3 not D2 don't know if they're the same.