Flashing engine light usually means the immobiliser is active.
Have you dropped the ignition key, or had the key open for any reason? There is a small black/grey transponder chip inside the key, dimensions about 7mm x 3mm x 2mm.
Lost or displaced chip is the most common cause of immo problems on Vauxhalls, the rest of the system is pretty robust.
Do you have a spare key you could try?
vaux, January 2011
