Mysterious moving cursor

I have a Dell Studio 17 that I have had since Feb. of 2010.  After a year of Dell support trying to fix the problem with mulitple hardware changes and complete system resoration multiple time they are telling me that it is normal for the cursor to move on its own when the lid of the computer is closed and you are using an external montior, keyboar and mouse.  This will happen even when the touchpad is disabled and the mouse and keyboard are disconnected.  The cursor will move and actually sometimes close windows that I have left open.  This is normal and they will do nothing about it and that seems amazing.  I guess I am going to have to buy an Apple.

Bob Helm