I apologize if this is actually an issue with userial or Windows.

Code can be found here: https://gist.github.com/ezrarush/01741135c7141621210c

Using userial with usocket's datagram socket causes an intermittent error.

Socket error in "sendto": 10014 (The system detected an invalid pointer address in attempting to use a pointer argument in a call.)
[Condition of type SB-BSD-SOCKETS:SOCKET-ERROR]

Using an array instead of userial's buffer does not seem to error.