I've got the same exact thing here (brand spankin new AB 10K 175w bulb with older style Corallife ballast that has a Magnetek transformer & cap).
Very first attempt to fire got absolutely NOTHING.. Second time and the sucker scared me 1/2 to death (flashed erratically for a few seconds and stopped.) Now it might flash, might start out dim and then gain intensity, hard to say.. Generally if it flashes it'll pop off and that's it, I have to flick the power off and on a couple times until I can feel the ballast give a good strong hum. - Otherwise if it starts out dim it'll generally warm up.
This is all over the course of the last 3-4 hrs trying to get set up.
I've only got another hr before the timer kicks off, but I'm thinking of overriding it and leaving it on for a good full 24hr cycle. (I only have fish/crabs/snails with the exception of a hitchhiked zooanthid.)
I'll let ya know how mine fire after lunch friday.. I'm gonna let it burn in for a bit. (Besides, the astreas could use the extra food!)
BTW - If it does look like a ballast issue, I'm probably gonna order a DIY from 1000bulbs.com - pretty good prices on DIY kits from what I've seen..
Good luck, I'd like to hear some more on it...