Thread:Project:Support desk/Weird Navigation items in Sidebar

So trying as best I can to get the 1.23 Monobook skin up to the functionality that we had previously...

And seemingly out of nowhere, some strange stuff appeared at the top of our navigation bar, here: http://awoiaf.westeros.org -- I've no idea where that random S or its lavel p-.3c-label came from.

It did appear after I attempted to use the PCR GUI Insert extension to try and place an ad unit in that sidebar, but even after removing it, and even removing the extension, the problem persists. I've looked in SkinTemplate.php and my base skin to see if a stray typo somewhere has caused this, but I'm running empty. Any thoughts as to how I might discover the culprit?