Vauxhall Frontera Help Needed?

I have a Vauxhall Frontera 2.0 SWB Transglobe 1998.

I have problems with it seeming to start only when it feels like it.

I get in the car put in the key and more often than not, the engine lights starts flashing. After 5 mins or so (opening and shutting door, taking key in and out, locking and unlocking), the light remains on and i can start the engine and drive off. This is annoying but i put up with it.

Im asking for any suggestions as to what it might be as, it happened to me yesterday at the petrol station and i was stuck there for 40 mins doing this whilst getting all sorts of evil glances off other motorists who wanted to use the petrol point.

Its so frustrating cause its a brilliant car, its just so unreliable at the moment.

Please help.

thanx