X server growing with out bound

[Douglas K. Rand]

I've recently replaced my old workstation running FreeBSD 6.3,
xorg-server 1.4_4,1 and nvidia-driver 100.14.19 with a new one running
FreeBSD 7.0, xorg-server 1.4_4,1 and nvidia-driver 162.12 and on the
new workstation the X server seems to grow with out bound, causing me
to have to restart the X server every few days.

On the old system here the X server:

USER   PID %CPU %MEM   VSZ   RSS  TT  STAT STARTED      TIME COMMAND
root   772  3.1 15.3 280804 238884  ??  Ss   20Jan08 1761:05.23 /usr/local/bin/X :0 -auth /usr/local/lib/X11/xdm/authdir/authfiles/A:0-QvpfCq (Xorg)

And on the new system:

USER   PID %CPU %MEM   VSZ   RSS  TT  STAT STARTED      TIME COMMAND
root 35061  3.1  9.8 1027484 203664  ??  Ss    4:47PM   6:41.43 /usr/local/bin/X :0 -auth /usr/local/lib/X11/xdm/authdir/authfiles/A:0-c2ZMy4 (Xorg)

Note that the old X server has been running for about 7 weeks, and I'm
lucky to get 3 days out of my new one. And even after 7 weeks the old
one has a VSZ of under 300 MB, while the new one starts out at about 1
GB, and keeps growing.

What will happen is that the VSZ on the new server will just get
bigger and bigger until it eventually reaches around 2.8 GB, then X
starts throwing errors like this one from "xv -max -quit -root":

  insufficient memory in X server to store root pixmap

I have, from habit, this in my /boot/loader.conf which is why it gets
to grow this large:

  kern.maxdsiz=2048M
  kern.dfldsiz=256M

Has anybody else been having problems like this?