I've seen a lot of complaints about the S2440L monitor. This is the monitor that I use and it too flickered and also would black out periodically. I returned the monitor and exchanged it for the same model. The new monitor started doing the same thing right away.
I believe I have figured out what it is. The power cord has an extension that plugs into an adaptor of some sort. This connection is terrible! These two pieces really weren't made for each other. I picked this section up and immediately the monitor flicked off because the circuit was broken. What we're probably dealing with is a poor power connection.
What I did is fold the cord over onto the adaptor, making sure it caused the plug to be snug in the adaptor and duct taped it. Thus far, zero flickering; zero black screen. Ghetto but it works!
