Scroll Bar on Touchpad not working?

I have a Dell 1520, and the scroll bar on the touchpad keeps freezing, so everytime i get this message "Dell Touchpad Enhancements have stopped working", then after getting the message you can't scroll up or down using the scrolly thing on the touchpad, however the mouse still function fine.

I have been able to fix the problem temporarily by re-installing the dell driver for the 'mouse and keyboards', however this just fixes the problem for a few hours, then afterwards the scroll bar quits working again.

Has this happened to anyone else, how can i fix it?

Thanks,