VPCF1390X - Blank (or black) screen

Hi,

I have a VPCF1390X for couple of months and I am facing a recurrent issue. Just to be clear, I am not using the hibernate or sleep mode (deactivated), and this happens with or without the battery plugged.

Once in a while, when starting my vaio (cold start), the screen will remain blank and no VAIO logo will be displayed but the power LED is ON and the fan is running sometimes smoothly, sometimes noisily like for a warm CPU even though the laptop was off for hours. I can wait for long, nothing will change and the HDD LED remains off...

Ctrl+Alt+Del and other F-keys do not work at all. The only solution I have is to push the Power switch for couple of seconds to turn off the laptop and then to switch it on again. Then usually, everything is running smoothly, I will have no message that Win7 hanged up before, and the laptop will work fine.

So for me, it sounds not connected to an OS issue but more a hardware one (boot issue).

In parallel, I performed a whole bunch of memory and HDD tests available with Win7 and Vaio Care and nothing wrong was found.

I have been through many forums and the only clue I found is about a voltage capacitor issue that could explain my situation.

Does anybody have an idea about what's going wrong?

Any help will be appreciated. Thanks!