We picked up our 2 emacs from my son's school today. They made it very clear that once you left with them you absolutely could not return them. Both worked fine at the school (of course). So, now that we have them home, only one of them works fine. The other won't go past the blue screen. I tried booting in safe mode but it says "System Failed: CPU=0 Code=0000008 (unaligned stack). I'm a total mac noob...what should I do? Thanks in advance!