I am having a strange problem with my daughter's Mid 2009 MBP 13". It will only charge with the charger that she regularly uses. We have tons of other chargers in the house, but not a single one of them works with that particular Mac. They all work with my 2011 MBP 13" and even with our white MB 2007. Another problem has been that the Mac would randomly lose power and shut down when she unplugged the charger from the MBP. I thought it could be the battery, so I bought a new one from iFixit and replaced it without a hitch. That seems to have solved the insta-shutdown problem. But the MBP still refuses to charge with any other charger. What can I do?