Why do I get a prompt for a password when closing Excel or taking some other action in Excel?
This is an Excel bug that happens to some Excel uses at different points. It is no longer very common and is generally caused by virus checker’s that try to decompile the addin. This triggers Excel to put up a password prompt. The fix is to teach your virus checker to stop checking Excel addins for viruses in this way or to get a different virus checker that behaves properly as it interacts with Excel.