Using Classic Outlook on Windows for personal email, calendar, and contact management
Dear Guillermo Lanza
Good day! Thank you for publishing in Microsoft Community. We are happy to help you!
Based on your description, I already understand your problem in general, actually an add-in is to blame for locking the message. In particular, we've found that Evernote's add-ins will cause this problem. Disabling your add-ins. It may be work again:
1. In Outlook, go to the File tab.
2. Select Options.
3. Select Add-Ins on the left
4. Near the bottom of the window, you'll see a Manage option; set it to COM Add-Ins and click Go
5. De-select all of the add-ins and click OK
6. Restart Outlook.
Things should now work normally. You can then go back and start re-enabling the add-ins one by one until you find the one that's causing problems.
In addition, please kindly repair an office application and check the result about the issue. For that you can refer to this article Repair an Office application - Microsoft Support
Also, you can try to start outlook in safe mode and check the result. For that following are the steps.
1. Choose Start > Run.
2. Type Outlook.exe /safe, and choose OK.
Note: There is space between outlook.exe and /safe.
Meanwhile, if your problem persists, please kindly suggest the user to use account to login OWA(outlook web app) and then check whether will get the same error, thanks
Thank you in advance for your understanding! Your patience and cooperation will be greatly appreciated. I hope all the best!
Sincerely
Kerry Chen | Microsoft Community Moderator