I run a software support team. You can't believe how many times we ask that same question and the customer says, "I don't know. Let me ask my IT folks and call you back." Then they call back and say, "They told me IE6."
I was just shooting in the dark.. was hoping he'd say IE6, then we'd know what the problem was.
ashpkt, I'm honestly not sure. Sometimes things like that happen during an internet problem. Such as excessive traffic or in-and-out bandwidth issues. Could also be some hyper security on your IT departments end not liking a particular image on a page or something.
What is frustrating is how random the problem is. I'll try to pay closer attention to see if I can identify any variables contributing to it.
Usually if our security doesn't like something it just scrubs out the individual item, like an Ad on a page. If if didn't like the page itself, I wouldn't be able to see anything but the Corporate Web Filter Violation message