The security light in my sisters 95' Cutlass Supreme will illuminate from time to time and go out. If you shut the car off, it starts right back up and the light goes out. I bought the car myself in 1998 and I had the same problems back then when I used to drive it, but now it won't start from time to time so you have to sit and wait three minutes for the system to reset and then it will crank. She is worried about getting stranded...the pellet in the key looks fine, not worn or dirty...what should we check for??