Starting problems - immobiliser fault?

[tezmc]

Hi,

I've had an intermittent problem with starting my car. Sometimes it will fire up, then cut out a second later. I noticed that the key light flashes on the dash when this happens. I have to keep turning it off and on again (without starting the car) until the light extinguishes.

This morning though, it just refuses to go out. Is this a known problem? How can I fix it? I'm a bit stuck now, I can't get to work!

Thanks