Flourescent lamp unit flashing when switched off.

I have recently replaced the normal tungsten filament spotlamps on each side of my bed with the new low energy flourescent units of about 7 watts. When these lamps have been running for some time and are therefore warm and I switch them off they flash for a few minutes. The period between the flashes is about 3 seconds and they are extremely dim. If I unscrew the bulb sufficiently to break the connection betwen it and the socket, the flashing immediately stops. If I hold the bulb, then the flash is much brighter, but the period between flashes is much the same as before. Sometimes, when the bulb is held and then released before the next flash is due, a bright flash is obtained, but the subsequent one is at the normal dim level. The bulbs are operated by permanently wired in domestic light switches which are wired 2-way with a switch unit by the bedroom door. As the light fittings are double insulated, there is no earth connection. No switch position changes or any other factors can be made to alter this behaviour which of course never occurred when the tungsten filament units were installed.

Any Ideas?

O.C.