Sometimes, your content management systems just cannot get what your database is telling them. The result: The Parser Error:

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In this case, it looks like it’s supposed to dish up a banner ad that the application cannot handle, resulting in havoc.
How do you find these things? Well, you just have to try to load the page. If you’ve got some sort of banner ad rotation algorithm going on, you have to reload the page. A lot.
A very basic automated test could do this for you; simply have the script load the page and use some navigation on the page. If the automated test bombs out, it could be because the navigation wasn’t there. Heck, even Empirix can handle that.
Wait a minute, someone just told me that Gopher was the Pacific Princess’s purser, whatever the heck that means. Oh, well, too late now, the gag’s done.