.\inc\skins\_skin.funcs.php

	if( !empty( $_SERVER['HTTP_USER_AGENT'] ) )
	{	// Detect IE browser version
		preg_match( '/msie (\d)/i', $_SERVER['HTTP_USER_AGENT'], $browser_ie );
		if( count( $browser_ie ) == 2 && $browser_ie[1] < 7 )
		{	// IE < 7
			require_css( 'ie6.css', 'relative' );
			$Messages->add( T_('Your web browser is too old. For this site to work correctly, we recommend you use a more recent browser.'), 'note' );
		}
	}

The regex returns only 1 digit, so if the IE version is 10, or 11 to come etc, it only gets 1 and thinks 1 < 7 .

This should work fine:

preg_match( '/msie (\d.{1})/i', $_SERVER['HTTP_USER_AGENT'], $browser_ie );