osx loading bar

That's a problem? Now, if it's frying hard drives, yeah: problem. But, what makes you think that?

 

That's usually indicating a firmware update being installed, but of course it isn't being installed each time. To see if there's one waiting to be installed, hold down the power button next time you turn it on (make sure of course it's not already on, because holding down the power button would force it off). The computer will emit a long tone and the light on the front will flash, and then you can release the power button. Wait for the progress bar to finish, then it should boot normally. If that doesn't fix the issue, I'd go back to the store and ask them to make it right. I haven't seen a major issue develop from that, but it often has indicated a software install that wasn't quite functioning correctly.

jW