Hi, and thanks for reporting this. Unfortunately, I am not able to sensibly work on this mod at the moment - its merely provided as a fork of the original Rate Calculator mod for those people who need it. If the current version of the original mod by raiguard works for you (in terms of the changed user interface), you might give that a try, it is much improved over this version (and likely less crash prone as it does not work incrementally).
Having said that, I also play exclusively multiplayer, and didn't yet see a crash with this mod - would your friend maybe remember what exactly he did when it crashed? Could it be related to some other mod also installed, or maybe did it happen while one player changed itemsa that the other player rate-calculated?
