In case anyone else has this problem (or if I forget!)...... You have to go to Edit > Sequencers > Arpeggio then specify the Key Range for the arpeggio, like you do with the Key Range for the tone. So I guess you have to do that as well as switch ArpEnable to off. Thanks guys
I'm sorry I still can't get it to work! I'm obviously missing something. I have done what maarkr suggested - the "Arp Enable" is set to NO - but still getting arpeggios where I don't want them Please help.