The Ernie Ball pedal, isn't it available in both 250K and 25K? Which one are you using? I would think the 25K would work better in the FX loop but don't know. I think the DFX unit in the DSL series can encounter situations that make it need to be rebooted like any other digital gizmo. I think sometimes it can be figured out what's causing it to need to be rebooted and help keep it from happening. Like AdrianDSL said above, maybe an impedance issue or something is tripping it up.