Did you or another user import contacts into this file from another file?
No I did not.
Nothing has been changed or added to the database.
Is there anything else I can check?
Just to confirm.
Here a screen shot of the problem.
When I click on the red arrow, nothing happens.
I've never had a copy of this solution, so I'd need to know a lot more before I could suggest much. There's a common issue with many templates that occurs when data is imported into it from another file, but since that's not the issue here...
Presumably this red arrow is either a button or is a graphic object on top of an invisible button. You'll need to check in layout mode to see what you have and what script this button performs. Then you'll need to check the script.