Prevent Auto Increment when extending cells down

[catamounts]

Hi everyone,
I have a spreadsheet that contains a date column (formatted as date). When it gets populated, users have a tendency to drag that value down to fill some of the rows beneath it. When they do, the date auto increments. Is there a way to prevent this other than asking all my users to hold down the control key when dragging or change some setting in Excel?

I should mention, this spreadsheet has some code that forces the user to enable macros in order to use the sheet, so a VBA solution would be okay.