Xterra pedals lock up and lights come on when put in reverse. CLUELESS & NEED HELP

txmac_9

This is something that has happened on and off when I put it in reverse. But sometimes I'll turn on my car, put it in reverse to back out of the space, and the gas pedal and brakes completely lock to where I can't push down on them at all. The car will roll if parked on a hill but I have no control. The only way to get out of it is to return to park, turn off the car, and turn it back on. Today I had to do that three times before it would stop. Has anyone had issues with this? What in the world could be making it do that? What repair should I expect to have to have done to fix it? PLEASE HELP?