I used to run a site using Server Side includes to look up template files to keep the look across the site (circa 2002 or so). My host had default 404 etc error pages which were write-locked but for some reason I could save over them in place, so I added SSI Includees to make the error pages match those of the rest of the site.
Later on, I rewrote the site in PHP, and since the SSI error pages wouldn't use PHP, and I had learned more in those days, I used a .htaccess page to point the server at new, PHP error pages, retired the old SSI based templates, and never looked back.
Unfortunately, one day, my host deleted the .htaccess file, so the server failed back on the old error pages, which still had SSI include links to template files that no longer existed. They also had the server set up so that on a 404 page not found during an SSI Include request, it would instead include the 404 page.
So we had a 404 page that would try to include a template file, which because it didn't exist, would instead include the 404 page in line, and so on... 404s all the way down, until the server ran out of resources and fell over. For all paying users on the node.
Biting the hand that feeds IT
