Hi guys, I have a the base 13 in 2011 model MacBook Air. For the past couple days is has been randomly shutting down while on battery power. It's at 74% battery, but when plugged in says either 'not charging', saying 'calculating time until full' and never displaying anything else, or it displays ludicrous amounts of time remaining until full (like 4-20 hours) I've tried all of the suggestions on http://support.apple.com/kb/ht3964 but so far it hasn't solved the problem. Restarting, sleep/wake, shutdown, and SMC reset all haven't done anything. I'm pretty sure the random power offs have only happened on battery power, but I feel like it was plugged in when it crashed while playing assassin's creed. The system information app says that the battery is charging, but it's been plugged in for a while and it hasn't moved from 74%. There isn't an Apple Store any where near me so I really don't want to have to mail it in and be without my computer. Any thoughts?