P Lock Malfunction when Parking

I have a new 2010 Prius, the car has 7000 miles and is not a year old yet. I travel a lot and sometimes I am gone for 10 days or more. I have this problem with the 12 volt battery that gets low within 8 days. So, it creates problem with my car and the system. Up to now I only had to recharge the battery and the car started no problem....but today I get this warning that is on the 2010 owner manual on page 510 " P Lock Malfuction when parking, park in flat place and apply parking brake securely the car is parked on a flat floor but the problem is I cannot get the stick to move from P to D....it is flashing on the dashboard and stuck on P?? Someone told me I need to reboot the system and to do this I have to disconnect the battery for a couple hours then the system will reboot and I should be OK......Anyone can help me on this? I am lost and I love the car and would love it more if Toyota did something about this 12 V battery not staying charged more than 8 days if the car is not used.
Thanks I appreciate the help as I am lost
Charles :rockon: