Typically, I let my monitor "sleep" during the day when not in use.  The other day, I went to "wake it up" and the screen would not come on.  It kept blinking or flashing (though not anything bright).  The power button was also blinking.  I tried to turn the monitor off but the only thing that would work was pulling the plug.  The next day I plugged it back in.  The monitor seemed to work fine.  But later when I went back to the computer, the screen did the same thing.  Is this something that can be fixed or is the monitor old (4 years)?