Paradoxically, this worked.

$100

Excellent docking station for MacBooks. Prices start from $60.

I've got the 2.0GHz MacBook (MA700LL/A) model.

"Apple has determined that a very small percentage of hard drives that were used in MacBook systems, sold between approximately May 2006 and December 2007, may fail under certain conditions. If your MacBook was purchased in the date range listed above and shows a flashing question mark on the screen, please take it to Apple or an Apple Authorized Service Provider and they will examine the hard drive to confirm if it is eligible for a replacement, free of charge, under this program."

"On MacBook, MacBook Pro, and MacBook Air computers with Multi-Touch trackpads running Mac OS X v10.6 Snow Leopard, the option to enable or disable "Ignore trackpad when mouse is present" is in the Mouse & Trackpad tab in the Universal Access System Preferences pane."

This is the hard drive that came with my MacBook.