Many thanks for your replies.
I have resetted the user bank to the factory presets. My problem now is how to get back my old sounds. Unfortunately I haven't saved them. I bought the XP50 second hand and the user memory was filled with the sounds of the JV2080. I'm missing a sound called 'Feed me' which emulates an overdriven guitar. From where can I get my sound(s) back ?

Regards,
Andi