Had one doing this a while ago turned out it was the immobiliser not recognizing the key. I replaced the antenna ring and car was ok. the starter relay is located in the n/s/f wing under the bonnet in the black plastic fuse box it is a black relay it is one of three relays in the middle i think. also i have heard that a bad connection on the starter sometimes causes this problem another thing to check is the multiplug going through the bulk head as these melt and cause all types of problems HTH ALAN