Everything Apple (the Mac heads thread)

Possible solution might be to start the computer in single user mode. (I am only getting this from wesbites)
From http://www.daniweb.com/hardware-and-software/apple/mac-os-x/threads/7694
Or

• Restart the computer. You may need to perform a forced restart as described in the Emergency Troubleshooting Handbook that came with your computer.
  
• Immediately after the startup tone, press and hold both the Command (Apple) and "s" keys on your keyboard. The computer will displays a series of text messages, at which time you may release these keys. When startup is complete, the computer will display a command line prompt (#).The computer is now in single-user mode.
  
  

How to Use fsck From the Command Line

Once you have reached a command line, follow these steps to use fsck:

• Type the following at the # prompt: fsck -y
  
• Press Return.The fsck utility will go through five "phases" and then return information about the disk's utilization and fragmentation. If fsck alters, repairs, or fixes anything, it will display the message:
  
  

***** FILE SYSTEM WAS MODIFIED *****

Important: If this message appears, repeat the "fsck -y" command until this message no longer appears. It is normal for your computer to require several "passes" of fsck, because first-pass repairs may uncover additional errors.

• When fsck reports that no problems were found, type the following command at the # prompt: reboot
  
• Press Return.
  
  

The computer should start up normally and allow you to log in.

Or http://support.apple.com/kb/TS1892