Why is my mouse/touchpad so sensitive so I can no longer type

This is entirely a new problem for me - My mouse/touchpad has become more sensitive so that when I am in typing programs I am unable to type properly (any light brushes with the touchpad means that there are substantial and unwanted changes in any written documents and it's wasting a lot of time - please help!)

A bit of background information - my operating system is Windows 7. I have quite an old model (samsung notebook NP300e5a, bought in 2009) so a lot of the online forums which I have looked at refer to more modern versions of the touchpad so I haven't been able to find a solution myself.

Actions I have taken:

- Control panel -I have altered mouse functions on the Buttons/Pointers etc tabs but it hasn't improved the situation ( I have returned these to their original position)

-I have checked and unchecked the 'Hide Pointer while typing' box but it hasn't helped.

- I have checked the related driver is up to date.

- I understand that I could use a USB mouse and perhaps disable the touchpad but I'm keen on finding a solution and returning the touchpad to its original state.

Many thanks in advance for your help and please let me know if you require any further information.