XHTML Validation, Plugins causing errors

Your 1st 5 errors can be fixed by editing your sidebar.php where you have:
Music
[:SITD:] Wegweiser
Suicide Commando Hellraiser (Psychopath 01-Version)
Tactikal Sekt Bring Me Violence
Das Ich Macht
Suicide Commando Mordfabrik

Simply remove the several <li> – you don’t need them with <span> in that instance.

#7 – Right before “Recent comments” in same file you have
<li><ul>
and below the comments
</li></ul>
Remove the <li> and </li>
# 8-9 Same file
Under “Archives” you need a <ul> before the <li> (actual dates) and </ul> after actual dates.

Hope this is understandable?

I took a look, and the error is caused by that music column of yours.

You have to have a <ul> tag before <li></li> tags
e.g.
<ul>
<li> a list item </li>
</ul>

Oh, sorry. I forgot to add the lines from my sidebar.php and from the scrobbles.php file.

This is what I have in my sidebar:
<span class="title">Music</span><br />
<?php scrobbles('Cythera'); ?><br />

And this is from the scrobbles.php file.
if(empty($format_string)) $format_string = '<li>%artist% %title%</li>';
if(empty($date_format)) $date_format = 'F jS Y @ g:i A';
if(empty($each_element)) $each_element = 'ul';

As you can see from the coding from the scrobbles file I have been trying to solve this on my own.
Right now the only error caused by scrobbles is a </> in the end of the music list.

And something with my archive list..
Which right now looks like this:
<ul><?php wp_get_archives('type=monthly&show_post_count=1'); ?></ul><br />