Prevent typing in a drop-down list to run macro
 

I have a locked and protected worksheet (& workbook) that uses
drop-down lists (not locked nor protected) with the source data located
on another hidden worksheet. I must have the spreadsheet check each
user entry from the drop-down list once it is entered, and then run a
macro after each change. The problem is that the workbook event of
"SheetChange" (or "SheetCalculate") won't work if the user types the
exact same available entry as in the drop-down list. The macro will
only run when the user selects from the drop-down list only.

Any help would be appreciated!