I haven't seen names with the iiiii ending that you mentioned. My first thought was that without realizing you might have hit the 'i' key when in the details screens, but you also said that you couldn't change the names. Maybe at some point the 'i' key got stuck and you got a corrupted file. Have you tried atrting another game in another player slot? Does the same thing happen?

(At one point many of my villagers had '`' at the end of their names. I realized that I simply missed the 'esc' key and the '`' was added.