I'm using async_send_to to send multicast messages. When I try to send data in a std::string, I always get a 'string iterator not dereferencable' assertion failure. I'm using boost 1.35 and VC9. Here's the code: // instance variable string buffer; // code in method buffer = BuildHailMessage(); socket.async_send_to( boost::asio::buffer(buffer), endpoint, boost::bind( &MulticastServer::HandleSendTo, this, boost::asio::placeholders::error)); I've also tried using char* buffer, dynamically allocating it based on the message length and then use std::copy to copy the std::string into the buffer, but I get heap corruption assertions when trying to delete [] it. The only way I've gotten this to work is using a fixed char[] buffer. Is there a way I can use a std::string with async_send_to? Do I need to use a different type of asio::buffer class? Thanks, John