My 2009 macbook pro isn't starting up correctly. First, safari started running slow. Soon after, the computer would stop loading at the blue screen. I'm able to get to the safe boot startup screen (where it asks for my password). I enter my password, click log in, the box disappears, and there's nothing on the screen except for the pointer and the standard purple spacey background for several mintues. The password screen then pops up again. This repeats over and over again. What might this mean? It's obviously the correct password since the box shakes if I enter a wrong one. It's accepting the password but not fully loading up. Thanks so much for the help.