It is the touchpad. You are inadvertently brushing the touchpad and
simulating a click which is causing the cursor to move. You should be able
to desensitize the touchpad or disable the click feature which should
resolve your problem.

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Terry Farrell - MS Word MVP
> Cursor frequently jumps to other places in text, causing the typing to
> appear
> in the wrong place; at times it jumps completely off the text and out of
> sight. I find it by pressing CTRL. What is the cause? I am using Word
> 2003
> on a Dell Inspiron 9300.