i have same problem..2003 alero 4 cyl. sometimes will start perfectly and then suddenly the car will crank but will not start...sometimes a security light comes on while driving but ran ok:confused: ...then for about a week later car wouldnt start so i had to reset the key for about 30 min. then will turn off key and then crank the car and it will start on right away...any tips on what would be the cause of this can be will be appreciated....thx

Sounds like a passlock issue