I read my mails in Gnus in an "emacs -nw" instance that I access via SSH
(this instance where I am writing this uses the same setup).  When I
have read my mails, I can make Emacs crash with the sequence <M-x a LEFT
RIGHT>.  GDB says this is in Fmove_point_visually at "BUFFERP
(g->object)".  I am attaching a GDB log with my commands added manually.

This does not reproduce without running Gnus before, so I can not run
this from a plain emacs -Q.  It looks to me like there is garbage in the
"row" struct, or the pointer row itself is garbage.

Let me know if I can do some more usefull debugging next time.