I would like to show "Suggestions" in my product listing in Magento. I made an attribute "Suggestion" which is Yes/No and global active. Now in the listing I would like to show the suggestions first, then some text and stuff, and then the rest of products.

I tried it like this:

$_productCollection=$this->getLoadedProductCollection()
/* .... */
$_productCollection->clear()->addAttributeToFilter('suggestion', 1)->load();

But this ends in an exception:

You cannot define a correlation name '_price_rule' more than once

Now the question is, how to solve this?