Laser pulsing instead of being continuous

Hi there !
Problems since a few days. Our 100W Ruida controlled laser cutter pulses instead of sending continuous beam. Same problem when engraving or cutting. It is not the dot setting. When I try to activate the beam from the controller, no problem before sending anything from Lightburn, then it pulses. You can hear a distinctive rzrzrzrzrzrz instead of the usual shhhhhhh. I have to reset the controller. No problem with RD Works so it is definitely Lightburn who sends a weird command to the controller. Any idea ?

Which version of LightBurn and OS are you using?

Win7Pro SP1 and LB 0.9.24. PC is not connected to any network and it suddenly stopped to work. But I cannot be sure if somebody touched something weird (we are a fablab)