- in Network.Socket: SocketOptions may include Linger, but setSocketOptions uses packSocketOptions, which doesn't know about Linger?

That looks like a bug, thanks.

And shouldn't Linger be on by default for the high-level Network lib?

It looks that way to me, but perhaps a Network Guru could comment?

- using hFlush does *not* seem to cure the problem??

That's worrying, and it perhaps indicates that there's another problem somewhere. I just tried a small test and hFlush does appear to do the right thing, so do you think you could boil down your example to something small that demonstrates the problem? Does it happen only on Windows, or Un*x too? Cheers, Simon