Unintended acceleration

Frighteninly, twice this month on my 2004 Prius with less then 1100 miles, without any warning my Prius has accelerated when my feet are off both the brakes and the gas pedal, the second time uphill! The only way to slow down the car is to jam on the brakes extremely hard until I get it to stop completely or to put the prius in neutral. When I put it back in drive or "B" my Prius started to accelerate again! While I had cruise control on earlie, cruise control was off, I know because I turned it on and then off again to make sure! I repeat no feet were on the pedals and this happended while going uphill. Both times I had been going at freeway speeds (60 mph +) and slowed down because of slow traffic, down to 35 mph the second time when it kept creeping up to 50 mph with my feet off the pedals. Im guessing that cruise control is mistakenly kicking in or that the accelerater pedal is not springing back up. Since I didn't think to stick my toe under the pedal while this was happening to force it back up I can't be sure. I've heard of some 2004's stalling on the freeway but not this problem. Otherwise I like the Prius, but this is so scary I fear Im going to have to sell it at with what the options and warranties were a $9000 dollar loss. Please advise, Thank you.
James,
2004 Prius owner.