On Thu, 7 Jul 2016 10:16:23 +1000 Venkata Balaji N wrote: > i left the system locked overnight. What are you using to lock the screen? Some of the screensavers can be bad news on certain video cards (as I've learned the hard way) and can cause just exactly that to happen. In that case, the screensaver has locked up your video card. If this is the case, try a different screensaver. I suggest "black screen only" for testing purposes. -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com