>It doesn't seem to me like a cert issue. The first time I go into UT it's always fine. It's when I navigate away from the site (without logging off), then use the back button to go back to UT, that I start getting the gray triangle.

Yes, that is what I thought as well. The authority who released the EV has verified all this and they confirmed it is ok. It might be related to a caching issue, such as a bug, when doing such navigation inside the browser.

>As for root certs - probably unrelated, but FF has been aggressive in revoking certs that have been deemed to be compromised. I'm pretty sure this doesn't apply in this case because getting in the first time is always OK.

Yes, so far, the only browser who had to release an utility to patch that is IE, such as I have applied a link on the main page to rectify potential corruption if the root certificates are no longer as valid as they should.