I have just had a similar problem today after years of having to have the EGR valve cleaned on a regular basis and the AA guy said to check the immobiliser. Car would not start - called out the AA who came within 20 mins and he started it first time. I am not convinced that what comes up on the dash is relevant at all times. Will get the immobilser etc checked and then get back and let you know if - or if not - this is problem.
John P, May 2012