TouchPad Issue

Hi All I just got an Inspiron6400 with Windows Vista Home Basic As soon as I connect my network cable to my laptop the touchpad starts behaving erratically.The mouse pointer does not move at all on some occassions and on others just vanishes to reappear at some other location. I restored the factory settings but still I face the same problem. Any idea how I can solve this issue? Thnx z ton in advance Gaurav