"A problem has occurred while trying to open this message."

If you have done the most recent update for windows 10, click on the "start" button.  On the very left side there are 4 buttons above the start button.  The top one is you.  Click on that.  Then click change account settings.  The first window that pops up will say your info.  Under your name it should say if you are signed in as an administrator. 

Have you installed windows live mail on this computer?  if you have ask Cortana to find windows live mail and when she pulls up the app in the window, right click on the app itself and then over to "more" and then run as administrator. 

I hope this helps.

I would like to try this solution ...         

The solution you refer to is intended to correct the permissions fault that arises for many users who go though the defragmentation procedure detailed earlier in the thread or encounter error 0x800C0155 for other reasons. Are you seeing this error?

I don't know how to ... "log on to Windows with an administrator account." 

If there is only one Windows user account on the computer, it will normally be an administrator account. Click on the start button and then on your profile image (it may be the generic one  ) and select Change account settings. The type of account (Administrator or Standard user) will be shown underneath the image on the settings page.

I imported Live Mail 2012 storage folders to Windows 10.  I can open some  of the emails in some of the folders, but not the emails in other folders. For emails in the non-functioning folders, I get the message that says a problem has occurred when trying to open the email. 

 I found the non-functioning folders buried deep in subfolders in the Live Mail folder. [Users\name\AppData\Local\Microsoft\Windows Live Mail etc etc.]   The individual emails are there, in the folders.  When I click on one of these emails, I get a message that says "The file . . . could not be opened because it does not exist or is being used by another application."  (0x800C013E.122)

Any ideas how to open the emails in these folders?  Is there a way to move these emails into different folders where they might open?

I would like to try this solution, but I don't know how to perform step no. 1--"log on to Windows with an administrator account."  I have a home computer with Windows 10.  How do I log on with an administrator account?  Thanks.