Hi Crispin,
I just tested this on one of our testing sites and it's working. I was going to ask if you had tried other pages but the referrer in the error you sent us was /favicon.ico so I would imagine this would happen on any page.
You swapped skins so that shouldn't be it (shouldn't be the problem anyway). Can you tell me what modules you have published on the homepage?
If you'd like to share info about the site privately, you can do so by emailing me directly.
The testing site(s) I am using are child.mtest-mssql.i7demo.com and mtest-mssql.i7demo.com.
Thanks,
Joe