Segundo o manual:

S motor overload. Paused...
Operation was paused because of large load on the spindle
motor. Click [Clear Error], cancel the paused state, then
resume cutting. Because the cutting may exceed the capacity
of the machine, revising the cutting parameters is
recommended.


No fórum da Roland eles falam que um dos problemas é o excesso de graxa para a lubrificação dos eixos.

http://www.rolandforum.co.uk/viewtopic.php?f=33&t=142

O manual segue no link
https://www.dropbox.com/s/3waqcyih8lu0232/MDX-540_USE_EN_R5.pdf?dl=0