Comment 3 for bug 296610

I'm running ubuntu 8.10. Myself and a coworker both have this same behavior with new Dell E6400 Latitude laptops.
For me it is pretty reliably triggered by typing anywhere near the touchpoint stick (the "n" key is particularly dangerous; holding it down is almost guaranteed to cause the pointer to "freak out". This makes it really hard to use the laptop at all :-(

After reading some of the comments on https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/+bug/34501 I thought that the kernel version might be relevant. I tried both 2.6.27.9 and 2.6.27.11 - no difference, I have the same problem with either kernel.

I looked at the LKML post mentioned by slowrobot above; the trigger described in that thread does not seem to be the trigger for the bug here. All I have to do is type on keys *near* the touchstick, such as "n". But the "lost sync" messages in that thread look the same here.

Don't know if this helps, but I've noticed that xinput reports different devices before and after an episode of pointer-gone-mad behavior.
WHen I first start X, xinput -list gives me this output:

$ xinput -list
"Virtual core keyboard" id=0 [XKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255
"Virtual core pointer" id=1 [XPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is 0
  Max_value is -1
  Resolution is 0
 Axis 1 :
  Min_value is 0
  Max_value is -1
  Resolution is 0
"Macintosh mouse button emulation" id=2 [XExtensionPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
 Axis 1 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
"AlpsPS/2 ALPS DualPoint TouchPad" id=3 [XExtensionPointer]
 Num_buttons is 12
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is 0
  Max_value is -1
  Resolution is 1
 Axis 1 :
  Min_value is 0
  Max_value is -1
  Resolution is 1
"DualPoint Stick" id=4 [XExtensionPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
 Axis 1 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
"AT Translated Set 2 keyboard" id=5 [XExtensionKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255
"Video Bus" id=6 [XExtensionKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255

Then, when the pointer starts acting crazy, I see this in /var/log/messages:

Dec 23 02:00:32 slinktopp kernel: [ 197.223741] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 5
Dec 23 02:00:32 slinktopp kernel: [ 197.224741] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 1
Dec 23 02:00:32 slinktopp kernel: [ 197.231699] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 - driver resynched.
Dec 23 02:00:32 slinktopp kernel: [ 197.249580] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 5
Dec 23 02:00:32 slinktopp kernel: [ 197.262458] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 6
Dec 23 02:00:32 slinktopp kernel: [ 197.267989] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 2
Dec 23 02:00:32 slinktopp kernel: [ 197.269139] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 1
Dec 23 02:00:32 slinktopp kernel: [ 197.270339] psmouse.c: DualPoint TouchPad at isa0060/serio1/input0 lost sync at byte 1
Dec 23 02:00:32 slinktopp kernel: [ 197.270350] psmouse.c: issuing reconnect request
Dec 23 02:00:33 slinktopp kernel: [ 198.445615] input: PS/2 Generic Mouse as /devices/platform/i8042/serio1/input/input12

After that "reconnect request", xinput sees totally different pointer devices:

"Virtual core keyboard" id=0 [XKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255
"Virtual core pointer" id=1 [XPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is 0
  Max_value is -1
  Resolution is 0
 Axis 1 :
  Min_value is 0
  Max_value is -1
  Resolution is 0
"Macintosh mouse button emulation" id=2 [XExtensionPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
 Axis 1 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
"AT Translated Set 2 keyboard" id=5 [XExtensionKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255
"Video Bus" id=6 [XExtensionKeyboard]
 Num_keys is 248
 Min_keycode is 8
 Max_keycode is 255
"PS/2 Generic Mouse" id=3 [XExtensionPointer]
 Num_buttons is 32
 Num_axes is 2
 Mode is Relative
 Motion_buffer is 256
 Axis 0 :
  Min_value is -1
  Max_value is -1
  Resolution is 1
 Axis 1 :
  Min_value is -1
  Max_value is -1
  Resolution is 1

I wonder if the change of device is what causes slowrobot's system going "back to the out-of-the-box slowness".

I also tried the modprobe -r psmouse && modprobe psmouse command mentioned by slowrobot; that brings back the ALPS devices reported by xinit.