Thanks for the suggestion. As I tried to describe above, when I access the same data locally, it works fine.
I have done some further debugging and found that the problem only occurs on HTTPS web sites. If I turn off SSL, it works properly.
Also, I am now getting a different error message when I access an HTTPS site, namely:
pkix path building failed: sun.security.provider.certpath.suncertpathbuilderexception: unable to find valid certification path to requested target
When I do a google search on that, it suggests a problem with my SSL certificate. Any known issues related to that?
Paul