Hier die korrigierte sidebar.php. Nicht getestet. Falls eine Fehlermeldung kommt, bitte bescheidsagen und meckern 
PHP
<div id="sidebar" class="sidecol">
<ul>
<?php if ( function_exists('dynamic_sidebar') && dynamic_sidebar() ) : else : ?>
<li>
<h2>About</h2>
<p>
<strong><?php bloginfo('name');?></strong><br/>
<?php bloginfo('description');?><br/>
</p>
</li>
<li>
<h2>Feed on</h2>
<ul>
<li class="feed"><a title="RSS Feed of Posts" href="<?php bloginfo('rss2_url'); ?>">Posts RSS</a></li>
<li class="feed"><a title="RSS Feed of Comments" href="<?php bloginfo('comments_rss2_url'); ?>">Comments RSS</a></li>
</ul>
</li>
<li>
<h2><?php _e('Search'); ?></h2>
<form id="searchform" method="get" action="<?php bloginfo('siteurl')?>/">
<input type="text" name="s" id="s" class="textbox" value="<?php echo wp_specialchars($s, 1); ?>" />
<input id="btnSearch" type="submit" name="submit" value="<?php _e('Go'); ?>" />
</form>
</li>
<?php get_links_list(); ?>
<li>
<h2>
<?php _e('Categories'); ?>
</h2>
<ul>
<?php wp_list_cats('optioncount=1&hierarchical=1'); ?>
</ul>
</li>
<?php if (function_exists('wp_tag_cloud')) { ?>
<li>
<h2>
<?php _e('Tags'); ?>
</h2>
<p>
<?php wp_tag_cloud(); ?>
</p>
</li>
<li>
<h2>
<?php _e('Monthly'); ?>
</h2>
<ul>
<?php wp_get_archives('type=monthly&show_post_count=true'); ?>
</ul>
</li>
<li>
<h2><?php _e('Pages'); ?></h2>
<ul>
<?php wp_list_pages('title_li=' ); ?>
</ul>
</li>
<li>
<h2>Meta</h2>
<ul>
<?php wp_register(); ?>
<li><?php wp_loginout(); ?></li>
<li><a href="http://validator.w3.org/check/referer" title="This page validates as XHTML 1.0 Transitional">Valid <abbr title="eXtensible HyperText Markup Language">XHTML</abbr></a></li>
<li><a href="http://gmpg.org/xfn/"><abbr title="XHTML Friends Network">XFN</abbr></a></li>
<li><a href="http://wordpress.org/" title="Powered by WordPress, state-of-the-art semantic personal publishing platform.">WordPress</a></li>
<?php wp_meta(); ?>
</ul>
</li>
<?php endif; ?>
</ul>
</div>
<div style="clear:both;"></div>
