On closing an email after no changes where made you get the following error messages :

The item cannot be saved because it was changed by another user or in another window. Do you want to make a copy in the default folder for the item

Do you want to save changes

This is a Com Add In interference, I recommend you go through all your Outlook Add Ins and disabling them and trying again until you pinpoint the problem. After you have found the addin, I would reset the Addin’s App Data Folder ( delete ) and also all the settings