97 Dakota Power Steering problem?

I have a 97 Dakota with 124,000 miles. Yesterday while driving in one of the worst snow storms we had in about 8 or so years, the truck lost traction & slid on pure ice. It did a 180 degree turn & the front end went up against a snow bank, but did not hit anything, including the curb. After trying to get it out but being uncessussful, I had to open up one of the sand bags in the bed (used for weight obviously), and putting some under both of the rear wheels; I was able to get the truck unstuck. However as I was backing the truck up; I realized the truck lost its power steering & also knocking type of sound from in the engine compartment as if something came loose. I never had any problems before this with the truck. I checked under the hood today & its not low on power steering fluid, the belt is good & tight, the pulley is spinning just fine & theres no sign of leakage or anything being loose or coming undone. Is it possible the power steering pump failed without any warning signs & is just a coincidence of happening at the time the truck slid? Or is there something I should check? Also I had (4) 75 pound sand tubes in the bed & the bed still slides as if theres no weight back there at all. I've owned plenty of trucks before & never had a truck that slides that much when it got 300 pounds of weight in the bed. Is that typical for the Dakota's? Do I need to add more weight back there? By the way it is a 1997 Dodge Dakota Club Cab 2 Door, short bed, rear wheel drive only, with like new all season tires installed. There's about one inch of pure ice outside with about 4 inches of snow covering that. Usually we don't get that much snow & ice. Any suggestions to stop the sliding & what to check before replacing the power steering pump? If the pump failed with out any signs, could that also be the noise I'm hearing now? Please keep in mind the noise started at the same time I lost all power steering.