Automatically Lock Cells When Data Entered

I am trying to apply a conditional cell lock to a worksheet. I am using Excel 2003, not 2007.

In column J, I have a list validation being used. The default value is "Not Claimed", I want to lock the cell from being edited once the value has been changed to any other value on the list.

The worksheet will be password protected to prevent entries into static fields (A:I & N:P).

I also would like to give the user the ability to unlock a specific cell, not the entire worksheet, by entering a password or something if they accidently choose a wrong value from the list.

I have column Q and beyond available if I need to have the password entered somewhere else.

I have attached a sample of the file I am working with.