After hours of searching the Dell Community forums and Google searches, I could find nothing that helped solve my problem. My Dell Inspiron 5559 just would not load the Intel Graphic Control Panel that I use to detect and control an older monitor used as a second screen. It had been working fine but all of a sudden failed to launch. All I could see was a thumbnail.
I tried changing the primary built-in monitor to a lower screen resolution. That worked! The Intel HD Graphics Control Panel now showed up. Once it was up I had it detect my second monitor and then returned the resolution back to the 1920×1024 recommended resolution for the built-in display.
Problem solved. I’m not sure what triggered this anomaly but it might have something to do with setting up a custom resolution on the second screen a few days prior. Dell cautions you that changing the display to a custom resolution could cause all kinds of quirky problems.
If you have both a Dell LCD Monitor and use a DELL notebook The IGCP may not be needed since Dell offers a Dell Display Manager for its newer monitors. I found it useful for working with the older non Dell monitor since I found that the built-in Windows Display manager would not reliably recognize the old Hitachi monitor. That’s what you get for using legacy monitors.