Try updating your BIOS to the A27 version available at http://supportapj.dell.com/support/downloads/driverslist.aspx?c=au&cs=audhs1&l=en&s=dhs&ServiceTag=&SystemID=LAT_E6400&os=WLH&osl=en&catid=&impid=
Try updating your BIOS to the A27 version available at http:// supportapj. dell.com/ support/ downloads/ driverslist. aspx?c= au&cs=audhs1& l=en&s= dhs&ServiceTag= &SystemID= LAT_E6400& os=WLH& osl=en& catid=& impid=