Synaptics Touchpad occasionally blocked

Binary package hint: xserver-xorg-input-synaptics

I have a (pretty old) Maxdata Vision 440T laptop with a new Feisty Herd 3 installation and a Synaptics Touchpad. Since Edgy, when I use the touchpad, it's occasionally just blocked and I can't move the cursor, click or scroll with the touchpad. After a few seconds or after scrolling the page with the arrow keys, it works again.
This problem didn't exist in Dapper, but I experienced it in Edgy and Feisty (only GNOME used). I haven't experienced it while using an external mouse.
According to the Device Manager, the touchpad is a "SynPS/2 Synaptics Touchpad".

Here's a section of my xorg.conf:
Section "InputDevice"
 Identifier "Synaptics Touchpad"
 Driver "synaptics"
 Option "SendCoreEvents" "true"
 Option "Device" "/dev/psaux"
 Option "Protocol" "auto-dev"
 Option "HorizScrollDelta" "0"
EndSection

$ grep -i synaptics /var/log/Xorg.0.log
(**) |-->Input Device "Synaptics Touchpad"
(II) LoadModule: "synaptics"
(II) Loading /usr/lib/xorg/modules/input/synaptics_drv.so
(II) Module synaptics: vendor="The XFree86 Project"
(II) Synaptics touchpad driver version 0.14.6 (1406)
(--) Synaptics Touchpad auto-dev sets device to /dev/input/event2
(--) Synaptics Touchpad touchpad found
(**) Synaptics Touchpad: always reports core events
(II) XINPUT: Adding extended input device "Synaptics Touchpad" (type: MOUSE)
Synaptics DeviceInit called
SynapticsCtrl called.
Synaptics DeviceOn called
(--) Synaptics Touchpad auto-dev sets device to /dev/input/event2
(--) Synaptics Touchpad touchpad found

If you need additional information, I can send some. Note that I'm not sure about the package that's responsible for the bug.