Thanks for the detailed bug report, and the tape!
In fact, this is another bug that I already fixed -- the reason here is simply that there were (quite a number) of occasions where the laser beam should have been deactivated (due to the fuse), but wasn't. It lead to the strange situation of the laser apparently being active, but in fact isn't (and therefore cannot melt ice etc.).
I think I should quickly release all those latest bugfixes with a new version 3.1.1 (and a corresponding new R'n'D version).
