I ran into the same problem with the same template.  It took me a few minutes to find the offending line, but once isolated, I inserted the line (referenced below) per Muffin Man's instructions -bingo. . . back to normal!    I'm curious like Nickza -does anyone know why this happened?  In my case I'm running this template on 1.5 RC3, but in legacy mode.  Could that be the issue?

error_reporting(0);
if ($color_index && isset($tab_colors[($tab_index)%count($tab_colors)])) {
                        $id .= $tab_colors[($tab_index)%count($tab_colors)];
                        $tab_index++;