Hopefully, there will be no more problems. You probably just had a corrupted cache or preference file that got overwritten when you changed the settings back and restarted.
However, things like this can be a sign of worse problems, such as hardware problems that can manifest in lots of ways. Keep an eye out for odd behavior.
Do you know how to do maintenance and repairs? Or back ups?
Go to Dr. Smoke's X-Lab site and read some of his FAQS:
http://www.thexlab.com/faqs/maintainingmacosx.html
This one is on maintenance but you can look around for others.
You also need to back up your hard drive just in case something more serious is going wrong. Dr. Smoke recommends Retrospect but I recommend SuperDuper! If you are a novice at back ups Retrospect will look intimidating but SuperDuper! is easy to use. Just get a Firewire external hard drive that is at least as big as your internal drive then you can make a clone, which is an exact duplicate. This means you can even boot off of it in case of problems.
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
Download and cloning are free, if you want to use some of the more advanced features and you need to buy it.
And no, I have no financial or personal interest in SD or any software in any way. I recommend what I use and like.
Kevin