I have a very large Financial spreadsheet in Excel 2002 that I am trying to work on. Every time I place my pointer on a cell to do an auto sum, after I click on the cell it will not let me leave that cell. Where ever I move my mouse, it highlights the whole page. I am unable to get back out of that cell. I have to "end task" in order to get out of that cell. Could someone please tell me why?