It's the code that parses the XML from the other site's RSS feeds. When their site cannot provide a nominal XML data as it expects it doesn't know what to do, hence that error and page breakdown you see.

Not nice, I know, but it requires proper error handling code to take care of this. If you know enough PHP and work with XML before you could fix it. I myself just don't have the time as much as I don't like to see it either.

Leaves you with a few options:

A) remove the external site feeds
B) fix the error handling code
C) just remove the one that is less reliable. (most likely the GameDev.com feed)