Well, OS X froze on me for the first time ever! Yay!
I woke up my PowerBook, but the screen didn't update. It displayed what had been on the screen before I put it to sleep. I experimented with quickly looking at the clock after waking up the PowerBook, and sure enough, it takes a second to update from the previous time. Something obviously went wrong, and it just didn't update. Thus, my PowerBook was frozen, and I had to force restart.
I know that in Windows, restarting incorrectly isn't good for the computer, causing loose memory fragments and random stuff like that. Is what I did a problem? If so, is there any way to defragment?