Strange Excel Mystery Window - need help fixing this...

[Number1]

I have a very strange issue going on as follows:

If I open a workbook, a "mystery" sheet opens up shortly after I open the workbook.
If I close the mystery workbook, it closes the original file I opened up.
There are no cells displayed and the ribbon is not displayed in the mystery workbook.
This installation of Office/Excel is only about three weeks old - recently had to re-image my PC.
Rebooting does not fix the issue.
Closing all instances of Excel and reopening the file does not fix the issue.
I have also tried repairing office but no success there either with the Quick Repair and Online Repair.
It is he Office 365 ProPlus version of Office.

I tried to include a screenshot of the mystery instance of Excel but could not figure out how to get the various HTML maker programs to include the screenshot when the code was generated so if someone can help me with that, I can post a screenshot of the mystery Excel instance.

Bottom line, what is this mystery instance of Excel and how to I stop it from opening?

 

[Number1]

To: My Aswer Is This - I think you are asking - what is NVidia - in the last part of your message. NVidia is the graphics/video chipset in my PC. They have a control panel application that is called Nview. That is the culprit causing the issue. Roughly a day after the NVidia update and have not seen the issue resurface - not out of the woods yet but looking good so far!!!