laguna II ignition problems

Hi all, have a Laguna II 1.8 16v on a 53 plate, just lately been having temperamental ignition starting problem, put card in and it just clicks, still have power to radio etc. etc., come backs few hours later and starts first time every time for next couple of weeks then will do same again.
could it be tdc sensor or more hassle with starter motor, seems to me as if immobilisor isn't being turned off sometimes.

many thanks

jason

laguna II ignition problems