MacBook Air Won't Restart


Within the last couple weeks my Mac Book Air won't restart or shutdown. At first I thought it was my external hard drive because I have both iphoto and itunes libraries on it. I would eject it and it still wouldn't restart or shutdown. It also freezes a lot lately to the point of control-command-power shutdown/restart. I reinstalled Firefox and don't think that's the issue. I also ran a utility on my external drive and it says it's corrupt (different issue). If Firefox freezes or stops responded I can't force quit it. I have to restart my laptop. We've had a few power outages and even though on a good surge protector, I power off and remove power cable.

Any suggestions???