DOS window appears briefly while working on computer

Greetings Group!

I have an annoying problem that I hope you can help me with. While touring my Home Page (AOL - yeah, I know, I know, it's because I'm 75 and it's what I've used all these years), at different times, a DOS window appears for just a second and then goes away. I'm curious as to what that window is showing, but it moves to fast for me to read or capture with "pause/break". I seem to remember a way to access the DOS but need a refresher. I am running the "ancient Windows Vista on my ancient computer. Can anyone help?

Thanks, Bob