I have been having the same symptoms for several weeks now..unable to log into the "secure" areas of itn that UAL uses. (I am also unable to log into the ITN.net website, but all of my other regular login sites are fine). UAL.com customer service was no help. I have found that if I edit the address bar, and remove the "s" from "https" I can access the "secure" areas just fine. It's very strange, only my home computer (using IE6) gives me the error message, my computer at work (IE5) has no problem. I think that maybe one of my Windows auto-updates caused this, since I didn't change anything myself, but I'm really stumped. If you figure it out please pass it along.
KV