[thelist] Form wont validate in XHTML 1.1

[Julia]

Hello again,
My page was valid XHTML 1.1 until I decided to add a form for a site search 
facility to it.
Naturally the validator has had the vapours, and is throwing up all sorts 
of error messages which frankly, I cant make head nor tail of!
Can some kind soul please tell me where I am going wrong with my code?
I am including the relevant  code below, and you can see the actual page at 
http://www.jewelswebgraphics.com/
It is the searchbox at the bottom of the centre column.
thanks very much...
Julia

<div class="searchbox">
<p><form action="/cgi-sys/entropysearch.cgi">
<input type="text" name="query" value="" />
<input type="hidden" name="user" value="*****" />
<input type="hidden" name="basehref" value="http://jewelswebgraphics.com" />
<input type="hidden" name="template" value="default" />
<input type="submit" value="Search" />
</form></p>
</div>