¿What BIOS are you using? Try updating to A16, it worked for me.
http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&os=WW1&osl=en&catid=&impid=&SystemID=LAT_PNT_PM_D600
¿What BIOS are you using? Try updating to A16, it worked for me.
http:// support. dell.com/ support/ downloads/ driverslist. aspx?c= us&l=en& s=gen&os= WW1&osl= en&catid= &impid= &SystemID= LAT_PNT_ PM_D600