I have a late 2008 15" Unibody MBP and recently started having a problem. Whenever I restart the computer and get to the login in screen to select an account I can't click anything with the trackpad, either by physically clicking or tapping the track pad. I have to plug in a USB mouse to select the account. Once I log in though the trackpad is fine and I have no problems clicking anything. I've tried taking out the battery in case there was swelling that was pressing on the track pad and I've turned off bluetooth but I still can't get it to click. I also tried booting from the CD that came with it and can't click anything, I had to plug in the usb mouse again to enter disk utility and do a 7 pass erase and clean install of the OS. After the clean install I restarted it and got the welcome screen and the problem still persists, I can't click the continue button to select a language with the trackpad but a USB mouse works fine. Any ideas what could be causing this and how I can fix it?