I established a validation list for a cell and had the "In-cell" drop down
box checked.  However, when I click in the cell, no drop down arrow appears.  
I type values directly in the cell and the validation criteria is active (i.e
it doesn't let me type anything not on the list).  I go to other cells in the
same file with the same results - no drop down arrow.  I go to other excel
files and try the same thing and it works - I get a drop down arrow and list.
The file I am working with is not protected.  

Any clues short of re-generating the offending file in a new workbook?

Regards,
JRV