novice needing help!

I bought a 1995 discovery a few weeks back, crunched a little going into 2nd gear if revs were high and a touch of knocking when releasing clutch. today was freewheeling downhill and the wheels all locked on (without use of the brakes!) the aa guy suggested the transfer box has gone - after moving the selector to tow it onto his truck. is this a regular problem? anyone any suggestions? thanks in advance for any help

anyone experienced a transfer box knackering up suddenly like this?

Hi, i bought a disco for breaking off a guy who had a similar problem to you.After breaking truck took gearbox off engine to find the centre off clutch plate had sheared and knotted it self up on pressure plate! Broke a good disco for a clutch plate gutted!