Restart Problem

Every time that I restart my powerbook, it freezes up. I did the software update and it froze up and I just restarted it a few mins ago just to do it basically and it froze up or something both times. It showed my desktop picture but just sat there for a long while. The apple light even went off so I closed the lid thinking it was off and put it to sleep but when I reallized it was still on, i opened the lid and there was nothing. I had to take off the battery to get it to start up again since I got nothing when i hit the power button. Does anybody have a clue as to why it's doing that? I've only had it a few days so I'm not quite the mac master yet. It starts up fine when I go through the normal shut down process though. Any help is greatly appreciated.