When I felt the random cursor jumps, I did suspect the touch pad and reduced it's sensitivity through control panel.Then I told my self that I set it right, everything will be alright. But for my surprise there is no change in the behavior, the cursor still jumps and i was stumped.
But after a small research I realized that the cause of the problem is not because of touch pad and it's due to POINTING STICK (rubber head ) which dell equipped for the lovers of Pointing stick. I found that when i typing something my fingers touch that pointing stick, that causes the cursor to move somewhere It should not and to disable it is the only solution.
We can easily disable it with Dell touch pad application...
To do that, Go to control panel, change the view to small icons, and double click on Mouse to launch mouse properties window or you can simply type Mouse in the windows 7 search bar and select mouse in the results.
In the mouse properties window, Click on Dell touch pad tab to launch the application. Once the application launched Click on Device select, In the device select windows click to disable Pointing stick and pointing stick buttons. or you can select disable touch pad/pointing stick when a usb mouse is present if you are using an external mouse.
Click apply, Ok. That's it. You're done. You disabled pointing stick and The cursor will not jump unexpectedly.. feel free to post back the results.
Hope this article will help you. Also have a look here to increase your battery backup