Man, you guys are boring!
Party arguments, internal rivalries, infighting and plots are an accepted part of the game 'round here; as is friendly-fire injury or death whether intentionally done or not. Oddly enough, such instances are often the stories that survive long after every other aspect of whatever adventure it was is forgotten.
Myself, I sometimes play goodly and-or co-operative characters and sometimes I don't; it all depends on what I've got in mind for its personality - and sometimes on how the rest of the party treats it.
An example of what can happen: one of my characters, a front-line Fighter, has been hit a few too many times by friendly-fire area-effect damage spells. So, he went out and got himself a Wizardslayer longsword; and now the party casters are on notice: hit me with your damage spells and this sword's getting used - you might get one more spell away while I'm charging you, so you'd better make it good.
That said, knocking off a character just because the player isn't there (as opposed to any in-character reason) is not cool.
Lan-"if your players are in fact killing other players that's a bigger issue: call the cops"-efan