Ialso had this myself a few times in 3.0.4 but usual a client reinstall fixed it, now everyone on server got it and nothing helps, can it be the java on server? what version should I be running there? I also added another line in the bat file instead of nogui too make it work at all I found here on forum somewhere.
Also I dont run EE so using transmuting is nto an option I tried throwing all the bugged items but the later another one does the same. including all stone from quarry mines up has the problem and most plants I harvest.