Two ideas on why you are having problems with the boot-up. 1. Have you checked the voltage you are getting. You say it works fine in the house but when you get to the car it isn't. Maybe you are shorting yourself somewhere. 2. Windows XP is funny about old, old hardware. I work with in everyday at a hospital and work with old PCs. Sometimes Windows XP just doesn't like it. Case in point, your 2mb video card. Just some ideas.