Only search results page broken

Would you have a non-production site where you can leave things broken for me to take a look at Craig?

I must say that it really bugged me (no pun intended) that it should not logically be an error on your part. I would clone the site for you but … I found an error on my part that only showed on that page.
It is still true that the search page was broken only when your optimizer was ‘on’ and not with it off. If you still want to investigate, I will gladly give you a platform to do it.
The issue was this code:

<?php if ( is_search() ) {
?> <div id="search_page_delete"> 
<div style="text-align:right;"> <?php echo wp_delete_post_link('* DELETE *');  ?> </div>
</div> <?php } ?>

The snippet that contained the wp_delete_post_link function was deactivated. Your optimizer broke the page in that state (because of my error). Making it active, thus a valid string being echo’d, all is well.
Hope that helps or if you want more info, let me know. THANK YOU for the quick offer of help.

so you ended up with a PHP error in the inner div? still weird that would cause the breakage indeed .. but happy you were able to pinpoint & fix!