XML parsing error
XML is a computer language that comes in many types, such as XHTML and SVG. XML must be "well formed" (free of syntax errors) to work properly. An XML parsing error occurs if an XML document is malformed. This article describes possible causes of this error.
Outpost Firewall includes a feature that replaces ads with the text "[AD]". Unfortunately, it does so in a way that if the page that contained the ad is written in XHTML, it produces a parsing error. To be able to view the problem website, you must disable Outpost's ad blocker.
Error in coding the page
The error may simply be a coding error that the webmaster made. Contact the webmaster and tell him or her your problem.