Comment 8 for bug 422224

The problem is that your touchpad doesn't support multi-finger touch. You can still try and see if multi-finger emulation (which is not guaranteed to work) solves the problem by playing with the values assigned to the following properties:

1) "Synaptics Two-Finger Width" which sets the pressure threshold to emulate a two finger press.
2) "Synaptics Two-Finger Pressure" which sets the finger width threshold to emulate a two finger press.

You can set these properties with the following commands:
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Width" 32 7
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Pressure" 32 280

and experiment with a value other than 7 for the former and with a value other than 280 for the latter, until you find a combination which works well with your hardware.

and of course you will also have to enable multi-finger scrolling (as you did before):
xinput set-int-prop "SynPS/2 Synaptics TouchPad" "Synaptics Two-Finger Scrolling" 8 1 0

If you find a combination of values which you deem acceptable, please let me know and also attach the output of the "lshal" command so that I can add a quirk for your laptop (so that those values are applied by default to the touchpad of your laptop).