Z axis plunging issue

Hello everyone , so my question is when I used the probe to zero my Z axis everything was fine but the second I started my carve the bit plunged down into the waste board. This issue never started until i started using my Jtech 7watt laser . Any tips to stop this .

P.S. : My laser was not atttached when I tried my carve all 3 times

Check your gcode file, do you see a G28 command in the early lines of code?