Any thoughts? It's happened twice. Screen rolls gray from top to bottom (can still see the window I was viewing) and a box pops up that says I need to shut down and power back on.

 

Haven't seen it on mine. I would take it in if you live near an Apple Store.

 

That's a kernel panic. Something is making the OS extremely angry, could be software or a hardware fault.

Try everything listed here, and if that doesn't fix it, visit your local Apple store or VAR.

 

Thanks, Simba. I'll try to hit the store tomorrow or Wednesday, or at a minimum call AppleCare support. Just for my knowledge, is there an easy explanation as to what you mean by kernel panic? I have no clue what a kernel is.

 

I general terms, the kernel the central component of the operating system that acts as a bridge between applications and the actual hardware. If something causes a fatal error the OS can not recover from, the kernel "panics" and halts the operating system. This results in the gray reboot screen you saw.

Many things can cause it, from corrupt hardware drivers to buggy applications to bad hardware. On a Mac, it's generally due to a flakey third party driver or a hardware error.

 

Thanks, again. Called AppleCare support today and the tech had me insert the flash drive that came with the MBA and archive & reinstall OS X. Literally as soon as I told him what happened he said OS needed to be reinstalled so I just went with it. We'll see if the problem occurs again.

Any thoughts on whether this action was off-base/unnecessary?

 

Depends. It's a shotgun approach to problem solving, though doing so eliminates OS issues from the equation. If you continue to have the problem, it's almost certainly a hardware issue.