Summary
This error most likely indicates a corrupted or incompletely installed System file. 

Details
This is an extremely rare error listed as "reserved" by Apple. The error can occur if you reset your computer or if your computer froze while installing System Software. If you receive this error while restarting the most likely cause is a corrupted or incompletely installed System file. 

If you were not installing system software and received this error, It is also possible for System Folder files to become corrupted over time. It is good practice to perform a clean install of all system software from time to time.

What to do
The easiest way to correct this problem is to start up from another disk (external hard drive, CD-ROM, Zip, etc.), delete the existing System files and perform a clean install of the system software. If you are booting from an alternate hard drive, Zip, or similar device, hold down the <Command> <Option> <Shift> and <Delete> keys at the same time to bypass the internal hard drive. If you are booting from an Apple CD-ROM drive hold down the <C> key to boot from the CD.

Written by
Jason McCormack
Technology Specialist
Baldwin Public Library (who received a free license for this submission)