Hi guys, thanks for posting a reply, but no it's not bracketing. I think maybe my description misled you slightly.
What happens is this: 1) Say I set up Manual settings at f5.6 and 125th Sec. at ISO 200
2) I frame my shot and half press for focus
3) Checking the viewfinder and it still shows f5.6 / 125th sec
4) Click - take the picture and it's overexposed, shot at f5.6 and a 30th Sec (or whatever). Now the data on the top LCD has changed to match what was taken, i.e. f5.6 / 30th sec
5) I've only taken one shot, it's not bracketing. So I reset to f5.6 / 125th sec, point and take another test shot - this time, different result and the shutter speed has changed again. It's not even correct exposures I'm getting so I can't figure out what is going on. Think I'll be sending it off to Nikon?