Possible security issue?

This may be unanswerable, but I had to try!
 
I'm getting a quick pop-up window in Windows 10. It flashes by quickly and unreadable. I've confirmed it's not the browser, because it comes up whether the browser is running or not. It's sporratic, between 3-15 minutes apart.  I've disabled the startup options I'm pretty sure don't need to be running and removedd some that defintely weren't. Checked the Event logs, and nothing besides the ordinary show up.
 
Is there any way I can track this activity and find out what this is?  I'm betting there's some kind of program that will log system activity that can grab that event.
 
Thanks!