I am working in a spreadsheet, and all is good. I select a range of cells in one or more column, copy a formula, etc. All the cells in the range reflect the changed data...but SOME cells in the range APPEAR blank! If I click on any cell adjacent to the blank cells and MOUSE OVER the blanks...the data becomes visible. Howver, if I click ON a blank cell and mouse over other adjacent blank cells, only the adjacent cells become visible; the blank cell I CLICKED ON reamins blank. I have to click on some other adjacent cell and mouse over this blank cell to make it visible.

This happens often, but not always. Any thoughts?