Most likely that socket adapter photocell is a simple one, which would fall in the category of a "2-wire". They operate by "stealing" electricity, meaning they allow a tiny amount of current to flow when the bulb is off. This current powers the device so it can switch the lights on at dusk. A regular bulb never notices a few milliamps, and does not light up or even glow. Because a CFL is an electronic device, this attemp to feed a small current through it causes flickering, and is bad for the bulb.
With modern bulbs, you have to be very careful with any type of dimmer, photocell, or motion sensor. Some controls say "no flourescent", some say "magnetic ballast" only, some say "electronic ballast" only. You have to know what you have, or as Clint Eastwood would say, a man has to know his limitations!