Using servo with arduino!

I finally brought the servos home and hooked them up to my arduino! Using some sample code, it worked great. Then I hooked up a 9v battery to the arduino's 5v regulator, and the servo started behaving erratically. Upon connecting the USB again, it is not responding. What happened?! I've run things on the arduino using a much more powerful 12v battery and everything was fine! Boo!! Hopefully it didn't somehow get fried. I'll post again when I know more :(