Can somebody try this link and let me know what happens?

If we try to access this site via the proxy server, we get the
following IE error (not a bordermanager error):

HTTP 403 Forbidden
The website declined to show this webpage
Most likely causes:
* This website requires you to log in.

If we connect directly (bypassing the proxy) the link works.

I've tried clearing the cache, but this link still doesn't work. I've
also tried configuring that domain as non-cacheable. No luck.

Any ideas?

We're running BM 3.8 SP5, with revision 30 of Craig's proxy.cfg file.