Jittery PS/2 Mouse in 7.0-RELEASE

[Alexander Dunn]

I have a PS/2, wired, optical mouse that I have been using flawlessly with
Windows and several Linux distributions for years now.  I would like to
switch
to Free BSD, but the mouse becomes very jittery within FreeBSD.  I have
tried
the mouse with both moused and X controlling the mouse, but in both cases
the
result is the same. The cursor on the screen tracks properly when I move my
mouse in a wide arc, but when I move the mouse in small increments the
cursor
does not follow the mouse at all.  This makes it very difficult to click on
small targets such as an OK button.

Relevant Information:

uname -a output:
FreeBSD kienjakenobi 7.0-RELEASE FreeBSD 7.0-RELEASE #3: Sun Mar 16 15:45:08
EDT
2008     root at kienjakenobi:/usr/obj/usr/src/sys/MYKERNEL  i386

dmesg mouse output:
psm0: <PS/2 Mouse> irq 12 on atkbdc0
psm0: [GIANT-LOCKED]
psm0: [ITHREAD]
psm0: model IntelliMouse, device ID 3

xorg.conf:
Section "InputDevice"
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "PS/2"
    Option         "Device" "/dev/psm0"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

This does not seem to be a problem with X for several reasons.  First, I use
this version of X.org with Linux with the same config that is shown above
without this problem.
Second, when I give control of the mouse over to moused, the problem does
not
change.  It is visible even in the console when using moused.

I am using a custom kernel, but this problem does not change even when I am
using the GENERIC kernel.

Based on this information I think I have crossed out most potentional
porblem locations,
but I hope I missed something.