Recalculate percentage is stuck at 0%
 

I have a big spreadsheet. I've set the Calculation option to Manual.

When I hit F9, it stays at 0% for a long time. and I'm afraid that I've lost
my file. Then all of a sudden it finishes and the sheet appears to be
recalculated.

Why doesn't the recalculate percentage gradually increase to show me the
progress of the recalculation?

(I'm using Excel 2003.)

Thanks.