http://bugs.winehq.org/show_bug.cgi?id=3254
--- Comment #64 from Henri Verbeet hverbeet@gmail.com 2009-06-04 04:42:14 --- Created an attachment (id=21540) --> (http://bugs.winehq.org/attachment.cgi?id=21540) secur32: Reset the read buffer after receiving an incomplete message.
You might need this one as well.