parameter and taxonomy problem

I have an issue.

I am have created page that will list all the posts of a certain type.

http://betawww5.pyramidanalytics.com/resources
I am trying to add filtering based on taxonomy

http://betawww5.pyramidanalytics.com/resources?types=video
This also works.

What is wierd is when i put a term that doesn’t exist
http://betawww5.pyramidanalytics.com/resources?types=vi

The website redirects me to a 404 pages.

I have added a 2 checks to the page.
1. Only include in the query the parameter if its set
2. Only include in the query the parameter if its a taxonomy/

if(isset($_GET['types']) && is_term($_GET['types'] , 'types' ))
{
echo "ilanb".$_GET['types'];
	$args = array(
				'post_type' => 'resource_page',
				'types' => $_GET['types']
				);
}else{
				$args = array(
				'post_type' => 'resource_page'

				);
				}