Alright, my powerbook has an older battery about 2 years and holds a charge for about 2 hours maybe, lately it has been making a really loud humming noise while charging, no noise when it is not charged. I assume i need a new battery BUT supposedly apples are able to run without batteries in right? I am not sure, but I thought i would try, I took the battery out, it started up until it got to the screen where my apps and folders start showing up and then it shut down. Any ideas?