SmtpMail hangs up

[Steve Wyatt]

I am using Delphi 2006, and having a problem with SmtpMail
(System.Web.Mail).

I have one D2006 VCL.NET project that uses SmtpMail to send an email with
attachments, and it works fine. I have another D2006 VCL.NET project (same
PC, XP Pro U2) that also uses SmtpMail but it hangs up at the call to
SmtpMail.Send(). After several attempts to resolve the problem, I
eventually cut/pasted the contents of the working project to this
non-working project, but to no avail. When I step through the non-working
project in the D2006 IDE, at the call to "SmtpMail.Send(msg)", the
application goes into limbo-land and does not come back; my PC is still
functioning, and there are no exceptions or error messages -- it's just that
the call to SmtpMail.Send() never returns.
I have even tried running both EXE's *outside* of the Delphi IDE -- the
working project continues to work, but the non-working project continues to
hang up.
Can someone give me ideas as to how I can go about debugging this problem?

(This is not exactly a "vcl.components" issue, but I figured this group
might be a good place to start)

Steve Wyatt