Evince fails to start because it cannot read .Xauthority

I’m logged in remotely over SSH with X forwarding to a machine running Ubuntu 10.04 (lucid). Most X11 applications (e.g. xterm, gnome-terminal) work fine. But Evince does not start. It seems unable to read ~/.Xauthority, even though the file exists, and is evidently readable (it has the right permissions and other applications read it just fine).