I have installed an external monitor (Dell ST2220L, 21.5 inch) on my laptop (Sony Vaio). I am using a DVI-D cable for connection. Since the laptop does not have a DVI-D port, I have connected a DVI-D to HDMI connector on the laptop end and inserted the cable in HDMI port of the laptop..
I have switched off the laptop display and adjusted the screen resolution on the Dell external monitor to 1920 x 1080 and adjusted colors for the Windows 7 and brightness and contrast from the monitor.
The problem is the monitor turns of blank intermittently for 1-2 seconds and turns on again at random interval. What could be the reason for this and how to get rid of this problem?
This seems to be a connectivity issue. Try and wiggle the adapter, and all the connections while powered, and see if you can make the problem appear. Don't forget to test the connection at the display too.