I had to shut down my computer today, which I don't normally do. Upon reboot, I noticed that it went to the blue screen after the apple logo, and stayed there for about 10 minutes before finally starting completely. This is a 24" 2007 alum iMac with 4 gb of ram. I don't have many things running on startup, Dropbox, Growl, Simplifymedia (turned this off), and a few other things. But what can I do to remedy this? I have only been using this computer for a few short months. What could be wrong? Thanks.