Comment 41 for bug 34501

I am sorry I can't reproduce the whole changes I made to my box in these last few days, however this problem has disappeared for me so far.
One of the noticeable changes was the kernel upgrade to 2.6.24-21-generic and a line in /etc/X11/xorg.conf

        Section "InputDevice"
        Identifier "Synaptics Touchpad"
        Driver "synaptics"
...
        Option "Protocol" "auto"

which was formerly "auto-dev".
I am sure I have never set the protocol to -dev (which I guess uses developmental code), however I changed now to standard auto.
After one week of 8 hrs per day work on the machine I have not experienced any scroll loss, nor system freeze (syslog does not report any of the previous error messages either).

Maybe you should give it a try and check if this works for you as well.