OK, have got the guitar home and uploaded the new flash (2.10) and was having a little play around and I think I now know what may be happening. The processor seems to be randomly scrolling through models (and possibly tunings). You could see this through Workbench HD one minute it would be on one then without touching a thing bam, another. And as I was on my custom sets, it sounded very strange jumping from Sitar to 12 string and then Les Paul randomly. This may also explain the volume changes from model to model.
Anyone else had this or know how to remedy?