From what I've noticed, I guess what happens is if the ballast has been on for a while and is hot, then for some unrelated reason it loses power for a second and turns off (ie..you unplugging it to plug in timer, lightning at my house, etc..), when you plug it back in (or when it regains power) it wont turn on right away because something is too hot in the ballast box or it has a delay or something. Basically, just let it sit for 4 mins with a fan on the vents in the box, then plug it back in and it should work.

I unplugged it just for a second today and this same thing happened with the blue glow...it just need to cool off...I had the fan on it for maybe a 2 or 3 mins and it worked fine after that, but you have a bigger lamp.

I dont know if all HPS do this, but the Gavita first starts with just a strong blue light, then fades to yellow then orange/red, etc..

And yes, its plugged directly into a wall outlet, but its going to be on an extension cord soon so I can put it back on the shelf.