Sorry that you have seen no responses on this scenario. Since reading this issue I have attempted to replicate your issue. However, I do not have a working Outlook 2003 program.

I was able to adjust all of the color modes in Outlook 2007 and 2010 with no issue for both myself and a test delegate.

I have also searched to see if this is a limitation with Outlook 2003 or if this option requires office 2003 to function correctly but have not been able to locate documentation to support this.

Does user B have office installed? If so what version? Also, Do you and user A have the full office suit?

Keep me posted,