About page not showing up

Hi gang, I did a search and couldn’t find this topic specifically. This is my fourth WP install, so I’m not a total beginner at this. I created an “About” page that goes to a “Page not found” error when I try to click on the link from the main page. The only thing I’ve done differently is change the permalinks settings to date and name based.

Any ideas where to look to troubleshoot this? Thanks in advance for your replies.