Simililar issue to mine except I lost everything... ended up being a crushed ignition wire running over the top of the steering column.... took a couple of days to find the damn thing and it only was a problem as a friend drove my car and moved the steering wheel from where its always been!
Could be many things....... i'd start with the ignititon circuits and start eliminating, your obviously getting the ignition at the barrel if your retaining reds so it would be after that which then eliminates out about 6 fuses that could be half on the way out! .....
Another possibility would be if you have an alarm and the immobiliser is playing up and activating even though the alarm isn't on..... guessing to would have ignition/spark & fuel cuts as standard....... have seen it happen but alot of the time the siren would activate also...
When driving, does it seem to be a bump or similar in the road that causes it to die or is it just random?