That error sounds a lot like a segmentation fault. Could we please see your code? It seems like you're using an uninitialized pointer or something.
As for in... that sounds like you forgot to declare something because AFAIK there is no std::stringstream "in"... again, do you mind showing your code? It would help us tons. ^_^
This is pretty off topic, but it always seems to me like the IDE is being ironic. That or the guys who write it never got the memo on unnecessary quotation marks. Which brings us to http://www.unnecessaryquotes.com/
Just so this isn't a completely unnecessary post, it sounds like you're trying to dereference a null pointer, no?