Load banging sound from the transmission?

Hi I wondering if any one can advise me on something I experienced on the weekend.

I am relatively new to 4 wheel driving and bought an NP 3.5 petrol automatic a year ago and have done some day trips in it with no real problems. The car had 83k when I bought it and had never been off road. I have only done about 4k in it in the 12 months I have had it.

Yesterday I was going up the Strickland Spur track, a steep rocky track just out of Marysville.

I engaged locked low range at the start of the climb. I got about 100 metres up the the initial climb and had experienced a bit of slipping on the rocks when I heard a loud meteallic bag sound which appearred to come from underneath the middle of the car. It was different from the sounds being made by rocks being thrown up. I stopped the car and everthing seemed alright so I started to climb again. As I moved on there was another bang followed a second or so later by another bang.

I stopped again put the car in neutral and tried to disengage the central locking and move back into straight 4wd. The locking light stayed on so I rolled back in neutral a foot or two before re-engaging locked low.

I was then able to climb to the top of the track, which would have to be a couple of kilometres, and then back down the track without any further incident.

The only thing I can think of that may have caused the banging was that the central diff lock hadn't engaged properly even though I had already climbed a reasonable distance up the rocky track or some how it had partially disengaged.

Has anybody else experienced this situation and shed some light on it?

On a different issue, I was climbing Rocky track in Toolangi on Saturday. This track is steep and is loose rock. Again I had climbed about a 100 metres when first the flashing traction control light came on, followed by a beeping audible alarm that then changed to a permanent sounding alarm. I stopped the car and the alarm cleared. I presumed the alarm was sounding because I was experiencing wheel slippage on all wheels.

Once I continue I got 20 to 30 metres further up the track where I lost traction trying to climb a small rock ledge. I rolled back a few feet in neutral and went back into drive. When I started to try and move the engine just free revved. I went back into neutral rolled back a few more feet and shifted back into dive. The transmission engaged and I was then able to continue my climb, albeit with the occasional audible alarm sounding.

Has anyone had any similar experiences in their Pajero?

Thanks