LCD flat panel monitor keeps blinking on and off

I have a Dell Dimension 4600 desktop, a couple years old.  I recently purchased a Hanns-G 19-inch LCD flat panel monitor.  A couple weeks ago it started blinking on and off when I first wake up the system.  The monitor keeps doing this for about 10 minutes, or until it warms up I guess.  Then, once it warms up, it tends to blink on and off whenever the CPU is cranking on something.  Is this problem something a video drive download might help?  Thanks for your help.