I concur with "Eye30".....I took my car in the other day to Hyundai, as I have experienced trouble starting the car, it happened 3 times last week. I took it in a few weeks ago, but nothing showed up on the computer and they said nothing wrong with it, and to monitor it!
last time it happened, I thought ahead and videoed me trying to start it, and was able to play this back to chap in the garage.
I also gave him a print out of the forum (i30 owners club) I had done some research on with the same problem and they sited the antenna(for the key transponder, part of immobilizer) in the steering column being faulty, in "many"
The response from the chap behind the counter was.."oh a forum...yeah well, there's a lot of rubbish on there, loads of people guessing at things, you have to take it with a pinch of salt'
...SO ANYWAY! I get a phone call this afternoon....."Oh hello, yes your cars already to be picked up! Yeah mate it was the antenna in the steering column, yeah they're quite common, we got it to come up as a fault code on the computer, so have re soldered the connection, you won't have any more problems"
Hope this helps