Wild guess: you're using a magnetic ballast?

Your bulb is dying. That's how MHs die -- not all at once, like an incandescent, but they have progressively more trouble striking. Electronic ballasts can help extend the life, although they don't work miracles; eventually all bulbs will die.

i understand that, but this was a 2 month old bulb at most. it shouldn't have died nearly that fast. i just thought that i got a bad bulb from the manufacturer and it should have come with a warrenty from defect or something similar.

Eh, that's the Poisson distribution for you :P

Obviously, nobody here can tell you what warranty some random bulb that you bought has.