Proxy / GSSAPI problem?

[Danny Sauer]

I'm unable to get Trac Explorer to work (from within TortoiseSVN, for
the record). I have a Trac instance on Apache, using mod_auth_kerb to
authenticate users from Windows. I can load the xml-rpc page in my
Trac instance from IE, but Trac Explorer just hangs essentially
forever and generates no log messages on the server (indicating no
connection) when I paste the same base URL in.

There is a mandatory proxy between the server and me. Is the proxy
likely to be causing the issue (ie, is trac explorer expecting no
proxy), or is GSSAPI causing the problem? I think GSSAPI is unlikely,
since fall-through to basic auth works fine in other programs from the
same workstation - including TortoiseSVN.