I'm developing an utility which communicates with an outside service by sending and receiving xml. On my machine it works flawlessly; on team's test servers also. On one customer's network we have to use a proxy - they are one of those police states, with security restrictions left and right.

The utility uses Rick's wwHttp.prg, which is basically a wrapper around Win API, HTTPGetEx() in this case.

This also works, but not always. About half of the calls work just fine, and the other half returns a "Win 32 API: The system cannot find the file specified.". However, when pasting the same URL into Firefox, on the same machine, I get the correct response, with full xml returned. In the same network, with the same restrictions. The FF is set to use system proxy settings.

Is there some proxy setting that I'm missing? What gives?