2005 Toyota Prius engine problems

I was involved in an accident with my 2005 prius on 3/29/2006. The cause of the accident remains a mystery. I was sitting at an intersection, waiting for traffic to clear. Witnesses reported that I pulled out into the oncoming traffic, resulting in a collision with another vehicle. Due to the injuries I suffered (a minor concussion resulting in retrograde amnesia), I had no recollection of the period prior to arriving at the intersection up until the paramedics removed me from the vehicle.

I have a 2005 toyota prius with 255k miles. I service my car regularly (about every 5 weeks). When I started my car after work, none of the dashboard lights came on. I put my car in drive and the car moved forward. I drove my car about 60 miles and stopped by the store. I became alarmed when the car wouldn't shut off. I pressed the "power" button several times but the car would not turn off.