When I try to access the touchpad settings they appear greyed out and cannot be changed. This problem arose after updating from KDE 4.4.3 to 4.4.4. (Kubuntu 10.04 backports).

I had set the VertEdgeScroll to be disabled and I notice in Konsole (when I run systemsettings from there) it says "VertEdgeScroll = format mismatch (32)" (among other things).

Where are the touchpad settings kept?

The Touchpad settings module isn't provided by KDE itself, thus its author may have a better idea of why this is occurring.

I would recommend checking all updates are installed, and checking to see if it occurs under a new user.

After an update the touchpad settings are now accessible. Fortunately, options have changed for the better from the previous KDE version.