Why is it that ssh with X11 auth forwarding fails -sometimes- on FC[23]?

[Dan Stromberg]

I've been making heavy use of X11 xauth forwarding.

However, I'm finding that while I can (mostly?) reliably forward xauth
data and $DISPLAY from an RHEL 3 host to AIX 5.1, Solaris 8 and others,
it only works with Fedora Core 2 and Fedora Core 3 -some- of the time.

In general, if I ssh -X enough times with an FC[23] system, eventually I
get good X11 forwarding (it seems to help to leave previous, failed
sessions open), but it seems to take from 2 to 6 iterations to get it to
forward - doing the -same- thing each time.

I tried turning off iptables on the FC[23] sshd servers, but that didn't
help.

I'm using "ssh -X -A".  RHEL 3's ssh client doesn't appear to support -Y
yet.

Any suggestions for me?

Thanks!