Updating charts in Excel

For some reason, my charts no longer seem to update when the source data
itself is updated. The source data cells are actually formulas themselves,
but they are updating with the new information just fine. It's very strange
that the table the values are drawn from have changed and are current but the
chart itself still shows old numbers. The only way I can fix it is to right
click, select source data, then re-enter the source data cells. (Actually I
change one cell and then change it back and it updates.)

Does anyone have any idea why my workbook is no longer updating cells? By
the way I am using Excel 2003. Thanks!

Jeff

We're having the exact same problem - if you get an answer from another source, post back to this group. Thanks!