Ballast or bulb problem

I have a 400 watt digital ballast currently running a 400 watt MH.
Lately it has been acting kinda funky. :wtf:

When it first comes on it will try to warm up, but then it starts flickering kinda reddish and goes out.
About ten minutes later it tries to start up again. Sometimes it will do this for almost an hour before it stays on.
Other times it comes on with no problems.

Is this a ballast or bulb problem?

what brand of digital ballast is it?

with digital ballasts...you need back-up lamps, available...change brand of bulbs, if possible?

or....switch to HPS setting & use HPS bulb

I forget the manufacturer name, but it was from HTG supply on e-bay.
It's a cheaper model.