Help! Metal Halide just stopped turning on!

It's only about two months old. Has been on an 18/6 timer since I had it. This one is a 400W Growbright MH conversion bulb in a 400W HPS ballast (not digital, not switchable).

It worked fine yesterday, turned off shortly before I went to sleep. I woke up at 8, it should have been on hours before that.. instead, ballast is buzzing (normal sound), and bulb is very hot, but no flickering, nothing.

Bulb doesn't rattle and looks fine.. haven't tried HPS bulb yet, waiting for the ballast to cool down.

Any suggestions? Please help!

it might just be the ballast is too hot and so has turned itself off,,,,,its a safety thing some ballast have built in,,,,,,get a fan on it to cool it down quicker,,give it 30 mins and the turn it back on and the bulb should come on,,if not,you need a new bulb.peace

Well. You might be right. I let it cool and then plugged it back in, worked fine..

But I notice a burning smell coming from the reflector/bulb (not ballast). It smells vaguely like burning rubber. There's no smoke and nothing visibly wrong in or around the reflector or bulb. I've always had the fan on so maybe that's why I never noticed the smell? It's not noticeable with the fan on - which is anytime the light is on.