What series is your Aero?
My S4 has a random selection of electrical faults eg Engine management light/seat belt warning light/loss of electrics, that can (usually) be fixed by rebooting the ECU. Switch the ignition on and off 3 times and pop the cut out seems to work for me. The cruise control has an odd problem in that it works fine when first used, whether the engine is hot or cold, but if used on a long run and then disengaged, then when reset the gear box changes down one or two gears for no obvious reason. Turning it off usually resets it.
I appreciate that your problem is different, but is compatible with the quirky nature of the car!
