If the high contrast setting is turned on you won't see the fill colour.
There's information in the following MSKB article:

OFF: Changes to Fill Colour and Fill Pattern Are Not Displayed
http://support.microsoft.com/?id=320531


ELYOD NANOC wrote:
FILL COLORS have ceased to appear in the Worksheet.
They do appear in Print Preview and in print.
How can I fix this?


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Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html