Ive just had the same problem - thought it was the immobiliser - had the ecu checked -all ok - there is a company called fuel parts that will check it for you for 55 quid - so started to check out the engine and wiring - i found the problem - firstly check that you are getting fuel to the fuel rail - remove plugs and check for spark - check injectors are working - if all is working apart from plugs and injectors i strongly recommend you check the relays - these are in a little black box at the back of battery - 1 is the fuel relay 2 is the engine control relay (ie plugs and injectors) - you also have 2 in the facia under the drivers dash - there is 2 main ignition relays - hold your fingers on top of the 2 purple ones and operate the ignition switch if you feel them clicking - then there ok - for the sake of 30 quid renew the engine control relay - that was my problem - if you still suspect the immobiliser - this can be checked by observing the red led light on the dash - if you need more help - get in touch - andy