hi pauline 4
if your car has an immobiliser it may be that it ,for no reason,came into operation. this some times happens and the car starts again and carries on without any further problem. i should not spend buckets of money having it investigated but carry on as normal. the computer stuff is next to useless. If you know your radio code, disconnect your battery for 10 mins, this will reset your computer readings to zero, and if it happens again they may be able to see a better read-out. if you disconnect your battery you will have to put in your radio code to get it to work, so make sure you have got the instructions!
good luck, alf