I turned off antivirus and still got the same VB error. So, I tried to narrow down the problem by opening .doc and .docx files from both File Explorer and Outlook.
I double clicked on two .doc and .docx files from File Explorer, and no VB error was generated. Interesting, so I thought I was onto something.
Then I e-mailed those same two files to myself, double clicked on them in Outlook and no VB error was generated there as well. Very strange.
I then tried double clicking on every one of those files multiple times and the error never showed up. This problem showed up a week or so ago, but I rebooted, it went away, so I just ignored it. It came up again yesterday, so I think it is an intermittent problem. I wonder if there is some software garbage collection that is not working that builds up over time?
Hope this data helps you guys find it.