7 - Views 3 - Displaying taxonomy description in a block
The URL is /taxonomy/term/% and I am using pathauto aliases.


If you're using aliases I assume that your URL is something like some/path/your-term-name.

In that case I had exactly the same issue a while ago. You should try setting Filter Value Type to "Term name converted to term ID and check "Transform dashes in URL to spaces in term name filter values".

Also make sure that proper value is provided to the filter.

In the WHEN THE FILTER VALUE IS NOT AVAILABLE section select Provide default value
and then select Raw value from URL and specify url component to provide as a default value. Unfortunatel "Term ID from URL" option doesn't work as you might expect in case of aliases so you need either provide default value from URL using Raw value option or even using PHP Code option. If you choose this option, you might find the following piece of code useful:

$get = explode('/', $_GET['q']);
return $get[2]; //the "2" constant assumes that your term name is a third path component