Automated Wndws 2000 HTTP call unable to link beyo

Here's a wierd one (for me, that is):

I have a web page on a Windows 2000 LAN, call it "A_THROW" on my server that gets called every 10 minutes by a scheduled process.  A_THROW, in turn, links to a foreign web page, B_CATCH, on a 3rd party's server.

As long as I run A_THROW from a browser manually (by typing 'http://www.mywebsite.com/A_THROW' into the address bar), (a) it runs and (b) it links to the off-site B_CATCH page and (c) B_CATCH runs

[both A_THROW and B_CATCH write log records]

However, when the scheduler process runs A_THROW, it fails to connect to B_CATCH, even though the log record shows that A_THROW ran fine.  I've tried different scheduler procs (SQL Server Agent, Cold Fusion Scheduler, etc) to no avail.  My belief at this time is that the policy under which these scheduled processes are running is somehow restricted from linking off-site, although I've never heard of that before and thought that ALL IIS web server calls on port 80 were processed as the same user.  Am I missing something here?  I'm stumped!
jimlord