|To DerbyDad03: Thank you for protecting me from a thoughtless mistake, your deletion is well appreciated.|
Thank you for your reply.
Is your drop down list based on a named range? Yes, it is. It lists 10 names: Sugar, manufacturing, tourism etc.
Is the option for autocalculate turned on? (I can't remember if that can be done on a sheet by sheet basis or the whole workbook.) The option in Formulas -> Calculation Options -> Automatic is ticked.
Did you create this sheet in 2010? The 6 data sheets of the workbook were created in Microsoft Excel 2010, (part of my Office Professional Suite).
Does the problem reproduce itself on other versions? Yes, I used a copy of my file on a different machine which is running Excel 2007, the drop down list function does not insert/work in any cell on any of the worksheets of my file. On a new, blank/empty workbook however, the drop down function inserts and runs normally.
Does the problem reproduce itself on other computers? See answer above.
Oh, and your title suggests 2010, yet the tag shows 2007. What version are you working on? I am using Excel 2010 installed on Windows 7.