problem with co-worker yaris, need opinion on what it could be.

[Adriaan]

This is the problem she has been having with her yaris. I think it is the Clutch Safety Switch, but the key part doesn't make sense to me. Here is her story let me know what else it could be, or if you need more info. I tried searching but not sure under what title to search for, stalling, key fob problem etc. Thanks

I was at the grocery store yesterday. Came out 15 mins later went to start my car and it started but stalled immediately. I started it again and same thing. The engine starts then I push the gas pedal the rpms go up but when I push the gas again the car doesn't respond and it stalls. I tried again and the starter kept turning over but won't start the car. I took the key out turned the key over and the car started fine?? got home and tried to duplicate the problem but it seems to be fine. I had this same problem a year or two ago. I took it to the mechanic and the code said the car thinks it's being stolen so it shuts the engine down. I called toyota's 1-800 number and they said it's the chip in they key. The chip only lasts for so long. So I started using my spare key and I haven't had this problem since. Until yesterday. I have a valet key that's new that I haven't used. I tried all three keys this morning but the car started fine. Have you heard of this problem? I've tried googling the issue haven't found anyone complaining of the same problem. I was going to take it to the mechanic again Tuesday after work, hopefully I make it to work. See what the code says again then maybe go to Toyota and see what they say? or get a new key made? I hate going to Toyota they want so much money for something that's hopefully not a big problem. My car is at 270,000 kms now. I've had the car new since 2008 and the first key lasted 5 years then the spare only lasted a year or two. Doesn't make sense. Could I drive using the valet key? Could it be an electrical issue? I don't believe it is cause it's only happened twice in so many years. Let me know your thoughts. Or what I should do.