Excel Pallet lost colors (hovering displays the colors but visual clues are not shown)

My pallet lost color-coding - if I hover over each little scare it displays the names for the colors and if I click on them they color the cells with the right colors, but the palette itself lost the visual display of colors except for 8 colors: black, blue, red, magenta, yellow, cyan, and white.

I use color-coding of cells a lot and I find it difficult to work without visual clues. At least the hover-help allows me to get the work done, but with difficulty.

Hope someone knows how to fix this.

Note: I search the forum and found a previous discussion with the 'default colors' sample spreadsheet. But copying the color palette from that spread sheet did not resolve the problem.

I would greatly appreciate any suggestions!

Martin, I have tried it - no luck. Here is what it looks like before and after the reset.
palette.png

Have you tried anything from this site yet: http://chandoo.org/wp/2009/02/13/help-on-excel-colors/

The article describes what Martin already suggested, but there are some people in the comments section that used other fixes and posted their approach. I can't really verify them, though.

Thank you all, I really appreciate all ideas.
1. I am not running accounting software
2. I have tried opening old spreadsheets that I have not used in years (and did not have this problem when I did use them) - I still see the problem. I was hoping to copy a 'good' pallet from an old spreadsheet but cannot find one that is good.
3. The problem is persisting I close and restarted excel several times. Tried creating fresh workbooks. I see this problem even when I start excel without opening any workbooks.
4. Reset did not do anything noticeable
5. http://chandoo.org/wp/2009/02/13/help-on-excel-colors/ had an addin that is supposed to edit the palette I am going to try that next
6. if that fails, I think my final thought was to uninstall and re-install the excel package itself.

Update:

I have run the tool and the repair (thank you for directing me there, I have not noticed it there and was surprised that the disk did not have a repair option).
Unfortunately, neither one of the steps changed the display of the palette.

I did not change any hardware.

However, I did open and save the spreadsheet with Open Office and then saved it in the excel format. I have done so in the past because Open Office compresses the spreadsheet very effectively, where as the Excel natively does not. This is a large spreadsheet and after compressing it with Open Office I can save and load it faster.

After the problem appeared, I have gone to the backup version prior I saved it with Open Office spreadsheet, so in theory that Open Office operation should have been totally negated. Or so I thought.

I have automatic daily backups of data each day, this gives me 6 days of history, so I can go back to any file saved in the prior prior 6 days. I have looked at every one of those backups, and they all show a problem with a palette.