https://bugs.winehq.org/show_bug.cgi?id=51289
--- Comment #1 from Zebediah Figura z.figura12@gmail.com --- Vista has an older networking stack, and the loopback path isn't reliably synchronous, which means that we generally have to wait for data to be available before doing nonblocking operations. I've had to deal with it many times by now.
I don't know why wvista isn't affected, though.