When I change the cell shading; either by clicking the "fill color" icon on
the Formatting toolbar or by right-clicking the cell, clicking, "Format
Cells..." and slecting a color in the "Patterns" tab; the cell stays white.
When I switch to "print preview" the color does show. This will happen in a
brand new Excel workbook with no special formatting. I even ran the "detect
and repair" wizard and reset all settings to defaults.