Just fixed a nasty bug that where recvfrom resets due to a call to sendto.
This is a bug in MS code and the solution therefore came from them
http://support.microsoft.com/kb/263823. Note that the
defineSIO_UDP_CONNRESET_WSAIOW(IOC_VENDOR,12) needs to be
define SIO_UDP_CONNRESET _WSAIOW(IOC_VENDOR,12)