i don't know why yur getting the error but a quick workaround would be to add them thru google and let them sync to yur phone until you figure out what it is. although i do recall way back when i got my phone i installed groupsU and some other contacts thing and it did that to me. i now use acontacts and its great. hope that helps.
Ya, that was mynext step if nobody had any advice. I'm gonna take it to verizon and see if they will possibly replace it, because my messages are constantly being deleted. Maybe they'll replace it with one without these problems