VS.Net 2005 on Win XP SP2

I'm trying to add a web reference to an external SOAP application written in
RemObjects, but when I attempt to add the reference I get an error message
saying "The proxy settings on this computer are not configured correctly for
web discovery. Press F1 for more information". I am not using a proxy server
or behind a firewall. Other people are able to access the service (from
tools other than VS.Net), but I am not. However, I was able to access it
briefly last week, but now cannot again. I am able to create a web reference
to some other services, such as this:

https://adwords.google.com/api/adwords/v2/CampaignService?wsdl
http://lottoexchange.net/LottoDrawings.php?wsdl
http://www.claudehussenet.com/ws/services/Anagram.wsdl
http://www.dataaccess.com/webservicesserver/conversions.wso?WSDL

The one I'm trying to connect to is in this format:

http://myservice.mydomain.com/project/something.dll/soap

One of the common remedies touted for this problem is to uncomment this line
in machine.config:

  <!--<add verb="*" path="*.vsdisco"
type="System.Web.Services.Discovery.DiscoveryRequestHandler,
System.Web.Services, Version=1.0.3300.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a" validate="false"/>-->

However, I do not have that line. If I were to add it, under what section
would it go? Since I am able to add a reference to some sites, and
occasionally to the target site, I presume this is not the issue.

*UPDATE:*

This would appear to be related to my ISP. If I put the web service address
in my browser bar I get "Page cannot be displayed", but when my friend who
has a different ISP does it, he sees the XML. I moved to his place and am
able to access it from here. The odd thing, again, is that I ~was~ able to
access it last week with the old ISP. My settings (as far as I can tell) are
the same. The old ISP denies that they are using a proxy server. Also, I was
able to access other web services even when I couldn't access the desired
one.

Any ideas? TIA.

[I initially posted this in ms.public.vsnet.general before I found this
group. Sorry for the cross-post]