EXIT vs. exit bug

Was helping troubleshoot a site today….they were having an issue saving driving direction updates to their WP page that was already published. When you would hit UPDATE from the admin interface you were taken to the live view of the site and shown the theme with the page content message “File Not Found”

First I updated them to 3.8, bug still existed.
Then I recreated the page from scratch, bug still existed.
Then I started pasting in the content line by line, updating each time. I found the offending sentence.
Then I found the offending word “exit” all lowercase as in “Take exit 48”.
I changed it to EXIT it worked. (I even changed it to exiT, which also worked.)

Hope this helps others.