Siometimes I let my Mac Pro run for days, and sometimes for hours. When it's hours and I restart it, it gets up and going fairly quickly. When it's been days, the restarting takes a lot longer (screen goes blue, spinning dashed circle on the screen). Sometimes this process seems like it's stuck, going on for over 5 minutes. That's when I press and hold the power button, and force it to shut off. When I turn it back on, it still takes a while to get back up and running. But not like when I've restarted after hours, in which cases I get to the desktop almost immediately. The question: What exactly is the machine doing during these pauses? Is there something I can be doing beforehand to makle it faster?