Thanks, Hood!
I was setting up a machine with SS and I found a strange thing:
E-stop was assigned, but not connected so E-stop input of MACH was continously active... I pressed RESET on the MACH screen several times (as I did not see this E-stop active issue) and Mach+SS froze.
Out of curiosity, I repeated this, and whenever I click multiple times on RESET (not fast, just 1 click per second) the system halts... is it normal, or a bug?