Protecting a cell, but allowing the drop down list to work.

In all versions of Excel except 97, locking a sheet makes Data Validation lists unusable if that cell is locked.

You'll have to leave the cell unlocked and use some additional steps to keep people from pasting into the cell, thus destroying the data validation settings...which I assume is your concern.

http://www.excelforum.com/excel-gene...l-editing.html