Harley Benton DNAfx GiT Pro

I have had one for 8 months now and until recently, it has been reliable and consistent. I use it in stomp box mode for four banks that cover all the music I play. I need clean clean, clean chorus , clean delay with tap tempo - and each of these are set up with the same dynamics, EQ, amp and cab models and an option to add distortion. The last bank uses the same basic set up, but kicks in a greater level of overdrive for crash chords and rock solos. I don't use an amp, but plug the box into the PA. So far, it has worked well and has never let me down until it did with spectacular fail on last night's gig - New Years Eve in front of a packed house. The distortion levels on all banks vanished to inaudible and the gentle chorus turned into a jet plane, yet at the sound check, all was normal. How could that happen? I am going to return all to factory settings and start again, but if this happens again, it is going in the bin. I need reliablilty.