I have a Spider IV 120 amp that I use with the FBV SHortboard MKII.  Lately, the amp has been shutting on and off when I try to play, like someone keeps hitting a reset or reboot button.  When I disconnect the MKII, the amp works fine and stays on so it has to be an issue with the MKII.  I tried changing the cable between the MKII and the amp but problem still exists.  Please help - why does the MKII cause my amp to shut on and off?

Thanks