Lock Flag ignored:How is this possible?

Hello,

Cells C4 and D4 are empty cells, and both are locked in Format Cells->Protection-> Locked.

I go to Tools-> Protection-> Protect Worksheet, use the default checkboxes.

Now it does not let me change the contents of C4, but it DOES let me change the contents of D4!

How is that possible?

This is Excel 2003.

I had the same problem with the entire 1st row ignoring the Locked flag, so I deleted the row and Inserted a new row, that fixed it.

But I can't delete this single cell (Pasting a working cell over the top if it does not fix the problem).

Why is this happening? How do I fix it?

That cell might have been one where I had been experimenting with pull-down lists at one point, but as I said, it is blank now.

Thanks,
Mark