I have done a battery calibration on my new 15 MBP. Usually, when it runs out of power, it goes to sleep, and when I charge it up, everything is back to what I was using. However this time, my MBP was not connecting to my network and the date was set to Dec 2000. So i looked up my network password in keychain access. When keychain access asked for my password, it would say access denied. I restarted the computer, same thing no network, nor keychain, and weird date. After about the 4th or 5th restart, i was able to check keychain access without the access denied and able to set up my networking again. I am just wondering if this is a common error or is it something I should be worried about.