I'm running Windows 7 Home Premium SP 1 64-bit on a HP 620 (just a year old). Lately, whenever I return to the laptop having left it alone for some time (Power Management set to 'Sleep' after 10 mins), and try to resume, I can hear the it resuming (fans etc.), however, the screen remains completely black. The only solution is to shut down the system manually and boot it up again. Can anyone help?!