R reg Vectra 2l CDX automatic gearbox warning?

sometimes when I start the car the 'automatic gearbox' warning is displayed. Usually when it is cold. If I turn off the ignition and then turn it back on it then works properly. This has happened randomely a few times over the last couple of months but has now happened twice in the last two days.

Can anyone tell me if its a new gear box I need or is it something much simpler, and hopefully less expensive