like the title said one of my player had send me a crash report and looks like it's coming from this mod here is the crash report http://pastebin.com/93wg5XBt

does this happens consistently? like every time he sees other players on his screen?
if not, this is just a rare case which i can't do anything about (it happened to me before with completely different modpacks, and i have no clue).

i'm not sure happen random. but if there more information that players can give me i will post it here thanks