logs out user unexpectedly

[Paul Cartwright <ale@pcartwright.com>]

we have 2 users on our system, and every 10 minutes my wife gets logged out, 
or it  restarts NVIDIA and puts her back at the login screen for me.
syslog shows this:
 kdm[4568]: X server for display :0 terminated unexpectedly

kdm.log shows this:
Backtrace:
0: /usr/bin/X(xf86SigHandler+0x81) [0x80c89c1]
1: [0xb7f65420]
2: /usr/bin/X(ProcPolyPoint+0xff) [0x808c1af]
3: /usr/bin/X [0x8154c9e]
4: /usr/bin/X(Dispatch+0x1a1) [0x808eff1]
5: /usr/bin/X(main+0x47e) [0x8076e2e]
6: /lib/i686/cmov/libc.so.6(__libc_start_main+0xe0) [0xb7d6a450]
7: /usr/bin/X(FontFileCompleteXLFD+0x1e9) [0x80761b1]

Fatal server error:
Caught signal 11.  Server aborting


X Window System Version 1.3.0
Release Date: 19 April 2007
X Protocol Version 11, Revision 0, Release 1.3
Build Operating System: Linux Debian (xorg-server 2:1.3.0.0.dfsg-12lenny2)
Current Operating System: Linux paulandcilla 2.6.18-6-686 #1 SMP Sun Feb 10 
22:11:31 UTC 2008 i686
Build Date: 19 January 2008
	Before reporting problems, check http://wiki.x.org
	to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
	(++) from command line, (!!) notice, (II) informational,
	(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Sun Mar  9 07:45:09 2008
(==) Using config file: "/etc/X11/xorg.conf"
(EE) Failed to load module "type1" (module does not exist, 0)
(II) Module already built-in
expected keysym, got XF86KbdLightOnOff: line 70 of pc
expected keysym, got XF86KbdBrightnessDown: line 71 of pc
expected keysym, got XF86KbdBrightnessUp: line 72 of pc
AUDIT: Sun Mar  9 07:45:14 2008: 16503 X: client 2 rejected from local host 
(uid 1000)

------------------
I can't find anything in any other log that points to anything obvious.
any clues as to why it is doing this?
running Debian Etch
$ uname -r
2.6.18-6-686

she has 1 cron job(other user has same cron job):
10,35 3,6,9,10,11,12,13,14,15,16,17,18,19 * * 
* /home/user/fetchyahoo-2.11.2/fetchyahoo  2>/dev/null 1>/dev/null

root has 1 cronjob:
# crontab -l
# m h  dom mon dow   command
05 11 * * * /usr/local/bin/rkhunter -c -sk


-- 
Paul Cartwright
Registered Linux user # 367800
Registered Ubuntu User #12459