strange multi-threaded problem on NT

Hello all,

I wonder anyone has seen this problem before. My app tries to fetch
documents following a list of URL's. When it runs in single threaded
mode (i.e. requests are made preemptive) everything works. Docs are
loaded successfully one after another. If I DON'T set the requests to
preemptive, more than one requests are active at once. More than half
of the requests will fail with a HTERR_SYSTEM error (error message:
connect: Unix errno=0 dec, winsock err=0) in the error list.
I can't figure out why some requests worked and some didn't. The
requests that fails appear to be random. From the same pool of URL's,
some requests will work in one run and fail in another. I have played
with the MaxSocket value and timeout value but didn't seem to help.

Any suggestions? Thanks in advance for any information.

I'm working on version 4.0D on Windows NT 3.51. The library was
compiled without WWW_WIN_ASYNC.

Paul Law