-rw-------   1 root  wheel  9392128 Nov 25 22:24 XFree86.core
$ gdb XFree86.core
...
(gdb) bt
No stack.

Since the releng snapshot of last Tuesday and I think every one
since, I have been having trouble with xdm's child process:

root     984  0.3 12.7 9928 33356 ??  Ss   11:27PM 0:01.65
  /usr/X11R6/bin/X -dpi 100 -depth 16 vt05
 -auth /usr/X11R6/lib/X11/xdm/authdir/authfiles/A:0

NetBSD 1.6K (GENERIC) #0: Mon Nov 25 02:46:58 UTC 2002
     autobuild@tgm.daemon.org:/autobuild/HEAD/i386/OBJ/autobuild/
     HEAD/src/sys/arch/i386/compile/GENERIC
...
vga1 at pci1 dev 0 function 0: ATI Technologies product 0x5446
     (rev. 0x00)

The sequence requires xdm to have been launched, a login session
to have been completed and logged out of. After logout, sometimes
xdm hangs, but every time, if one toggles to another wscons screen
the xdisplay shifts up, the current xdm session (or login window)
coredumps and xdm trys to restart it. Sometimes, the xdm child
process hangs and a simple kill or rc.d/xdm restart cannot kill
it. Sometimes the whole console input stream locks up and one is
sol without another box around to log into and kill -9 the xdm
session.

This may be related to the ATI card, but I'm not sure. I noticed
that about the same time that this started up, the ATI 50-line font
problem in the wscons screens was fixed but I may be off by a few
snapshots.

This problem only occurs with xdm. startx with twm or kde doesn't
see this problem.  The logfiles show nothing unusual.

Any ideas?