I spotted that situation several days ago. It's one of several things that was somehow in the wrong setting. But you're on the same path I was--every time I explored a new avenue it always kept coming back to something authorizing access to the information, and that something was most likely the firewall. I just spent the last couple of hours completely uninstalling my Norton Personal Firewall and Symantec Anti-Virus. I then installed them both, and as I worked, they were able to download what they needed. I'm back online. I don't know if the earlier "ipconfig/flushdns" in anyway helped, and I'm going to be resetting cookies for days as I go about my online business.
I haven't heard about any kind of a worm or virus or malware that resets firewalls, but something seems to have corrupted the system. It was a chance to get to renew my knowledge of my computer and software. (I just wish this kind of work was user-driven rather than equipment-failure-driven!)
Thanks all for your suggestions. This will drop off the page and be one more specialized resource for Mudcatters (and probably turn up in Google searches by outsiders).