Gateway Laptop Problem!?! The position of where I am typing moves...?

Ive owned a gateway laptop for about 18 months now and I reformatted it the other day because it was going horribly slow and since then whenever I try typing things like a word document or on a website the flashing text cursor will suddenly "tab" on to something else and i end up typing half of my sentence in the wrong place or not at all. Can anybody help me please its driving me mad!

Oh and I have installed all the latest drivers etc and it isn't me accidental hitting the mouse pad.