I received a Dell Latitude E6510, Windows 7, Bought January 2011

Problem: My text cursor jumps randomly around when I'm typing

I take care where i put my fingers: no result
I have the last drivers DELL_MULTI-TOUCH-TOUCHPAD_A06_R281462.exe
I deactivated the touchpad: no result

I have 2 other Dell (Inspiron and Precision M65): This problem never occurred

The question appears hundreds of times on the Internet. However no answer is helpful.