Well I don't think it was a noise problem, after tracing the USB cable to where it was plugged in (BTW, I was mistaken, I have an external connection), I tried rebooting without the MX plugged in. Since after reboot I was still getting the same error message, I tried reinstalling the LDCD software ...

Internal

I just started to get this message when LCDC first tries to start:

LCDC raised continuable exception and still will continue operating.
Exception was: '$/0' is not a valid interger value.

I also get it when I try to save a plug-in selection.
The auto detect in LCDC passed, so it doesn't look like ...