The code that produces the no results error message looks like:
<?php
if ("".($Search1_BOSS_all) ."" == "0") { // WebAssist Show If
?>
<div>No results found matching your search.</div>
<?php
} // ("".($Search1_BOSS_all) ."" == "0")
?>
assuming your search from uses the POST method, you could change that to:
<?php if($_SERVER["REQUEST_METHOD"] == "POST") { ?>
<?php
if ("".($Search1_BOSS_all) ."" == "0") { // WebAssist Show If
?>
<div>No results found matching your search.</div>
<?php
} // ("".($Search1_BOSS_all) ."" == "0")
?>
<?php } ?>
to hide the error on initial page load.