I had a similar problem with my 17" PowerBook. The dash key wouldn't work, but when I hit the return key, the dashes would appear-and they wouldn't stop dashing away-as if I was keeping my finger on the dash key. I never spilled anything on it, it just started doing this for no reason. It wouldn't go to sleep either.

I took the computer to the people at www.intosh.net and they replaced the keyboard...after trying to clean it. They were honest and hardworking. They only charged me about $100 for the keyboard and about $40 for labor. I had my computer the next day! If I had taken it to Apple, it would have been 3x the cost and minimum of 3 weeks without the computer.

Be sure to back up everything on your computer though, just to be safe.