The link to the subsequent collection pages is being written with an ampersand instead of a question mark. I'm not sure why it's happening, but that's the problem.
if ($num_pages > 1){ if ($current_page > 1){ $output .= ' <a accesskey="," class="pagPrev" href="'.$url.$separator.'plog_page='.($current_page - 1).$extra_params.'"><span>«</span></a> '; }
But this code could very well be perfect ;). If it really is a small error in the code it should be reported as a possible bug so that future users will not have to change the code themselves...