Cruise control problem C180 1997 Update

[merclover2004]

I was asking for advice regarding the intermittent operation of the cruise control on my 1997 C180 but I have discovered today how to get it to operate. The problem began when I took my car off the road for a few months and the battery was flat so I recharged it (without disconnecting it from the car) and when I started to drive the car I realised that the CC did not work.
I have today repeatedly observed that if I turn on the ignition and pause for a second or so before turning the key further to start the engine then the cruise control does not work but if I turn the ignition on and then immediately (without any pause or delay) continue to turn the key and start the engine then the CC works perfectly ever time.
Can anyone suggest why this might be? Does the engine computer sense some fault during start up when there is a delay in the ignition sequence therefore causing the CC to be disabled but when the car is started quickly then the fault is not detected? I would appreciate if someone knows why the speed of turning the key from the off position to the start position should affect the CC. Thanks