I know exactly what your problem is, the emoblizer is not regestering the code in the key so cuts the engine off. The reason you can start it is because, when you turn your ignition on, it fires up the fuel pump for 5 seconds. The imoblizer realises that there is a problem so shuts the engine down. You will need to take it to main dealer to get the imoblizer reprogramed but only if you are not doing anything wrong yourself, like for example, you may be using a spare key which hasent been programed, if this is the case then you will need to take the car and key to vauxhall for them to program the key into the car. I hope I have explaned this so that you can understand it. If you have any queries then e-mail me and I will help you out.
trit666@hotmail.com
Kind Regards
Tristan Hanwell, April 2006