I have Outlook on Windows 10 and sometimes when I try to send an email instead I get the message "The operation cannot be performed because the message has been changed." So I click on Save but instead of saving I have to make a separate copy in the inbox folder and send it, leaving a partially finished email in the drafts folder. Also I get the "message has been changed" alert when try to flag and unflag emails. I've been contacting Tech Support about it the past few weeks but to no avail. I've even uninstalled and reinstalled 365, and that didn't work. What should I do?