In an Excel 2003 workbook I have now on 4 occasions over about 5 years of usage found that the radio button for Objects on the Tools-->Options ( General Tab ) has mysteriously changed to "Hide All" instead of "Show All". Interestingly, instead of just hiding the objects in the workbook (that I have macro's attached to), it also disables the displaying of the data validation drop down lists across the entire workbook.

Is there some short-cut key sequence that I might be accidentally entering that causes this setting to change? Or is there something I might be doing in editing my objects or the macro's associated with them that causes this change? Or is there something in editing or adding data validation that I might be doing?

The seemingly undocumented disabling of the drop down list and its control by this "Objects" setting is surprising. I discovered it by accident.

I develop and maintain the workbook on one machine and send it for production usage to another. I seem to discover the problem only on the production machine. I assume the Option settings are a part of each workbook, not tied to a machine. I don't know if this has any bearing.