Okay I have a solution to this problem and I think this problem should be addressed by OSCommerce since Authorize.net will not and it is really an OSCommerce problem because the transact.dll page does a curl and tries to load the content onto a secure page and certain browsers see that as a security violation.
open checkout_process.php and replace this line:
tep_redirect(tep_href_link(FILENAME_CHECKOUT_SUCCESS, '', 'SSL'));
with this:
echo <<<END
<script type="text/javascript">
<!--
window.location = "http://"MYSHOPURL"/checkout_success.php"
//-->
</script>
END;
Replace "MYSHOPURL" with the location of your shop.
Note: This is a hack and not a complete solution because if an error occurs during cc processing the page will still be ugly.
More information on this problem can be found here