Hi JM,

I'm sorry to hear that you're having trouble changing the tab color in your Excel 2003 spreadsheet. Here are a few things you can try:

1. Make sure the worksheet is not protected: If the worksheet is protected, you won't be able to change the tab color. To check if the worksheet is protected, go to the Review tab and click on "Unprotect Sheet". If the sheet is already unprotected, move on to the next step.
2. Check if the workbook is shared: If the workbook is shared, you won't be able to change the tab color. To check if the workbook is shared, go to the Review tab and click on "Share Workbook". If the "Allow changes by more than one user at the same time" checkbox is selected, the workbook is shared. To unshare the workbook, uncheck the checkbox and click OK.
3. Try changing the tab color from the Page Setup dialog box: If the right-click menu item is grayed out, try changing the tab color from the Page Setup dialog box. To do this, go to File Page Setup and click on the "Sheet" tab. Under "Color", select the color you want and click OK.
4. Try repairing or reinstalling Excel: If none of the above steps work, it's possible that there's a problem with your Excel installation. Try repairing or reinstalling Excel to see if that fixes the issue.

I hope one of these solutions works for you. Let me know if you have any other questions or if there's anything else I can help with.