Hmmm #Windows8 #IE10 Certificate issues - anyone seen incorrect revoked

I've loaded the laptop (a touchscreen one) with the dev build of Windows 8.  So far so good.  The highlights have to be
a) it works!
b) it boots in under 20 seconds (and that's with a normal BIOS, not UEFI)
c) it installed in about 15 minutes from a blank disk to a logon screen

However, working from home, I was working with Outlook on the box and got some problems so thought I would hit the OWA site for my email, when I did so, I got this:

That was a bit of a showstopper!

So I've done the usual google thing, nowt.

I've tried the Outlook Anywhere connection - fails.

I then VPN'd into the network, and hit the Exchange CAS server with the local name and logged on fine. 

So the certificate is not revoked.

Further supporting evidence is the fact that ActiveSync is still working on the phones, and I can use OWA from the iPad.

So, anyone seen this?  Got a fix?  The only clue I can think of is that the certificate is for a non-standard name; it's not for www but owa.

Ta, Peter