'94 pathfinder grinding noise in right rear tire

i just engaged the 4-wheel hi on a recent ski trip. worked fine- re-engaged into 2-wheel drive. after leaving rest stop- the car started to make a grinding sound near the rear right wheel and the car started bucking and lifting, almost like i had a flat. got home okay in 2-wheel. this morning, took off from a stop-- did the same thing. then stopped, and i proceeded to drive into town. MOST IMPORTANT!!!-- is this car safe to drive? i have it parked for now-- any help would be great-- thanks