I've long been running Excel 2003 on my XP machine, but recently I've
had occasion to run the same workbooks under Vista. Which raises a
question.

Is there some way I can keep the calculation turned off, and yet keep
Vista from declaring Excel to have become unresponsive?

My workbook is essentially just a lot of VBA that optimizes a problem.
So the program can run for days if I choose to let it keep refining
the solution. To make it run faster I've turned off screen updating
and automatic calculation. At occasional points in the code I turn
the functions back on briefly to allow the screen to update its
progress for me, but basically these functions are off. And I update
a status message on the status bar for my convenience perhaps once a
second.

Everything works fine as expected under XP. With Vista however, after
running a few seconds, Vista will declare Excel to be "not
responding". The main effect of this is that the status bar no longer
updates (so I can't see what's going on), and the 'Esc' key which can
normally interrupt the VBA execution does not work. The program is
still executing, but it is silent and cannot be interrupted.

After fooling around with this I find that if I toggle the automatic
calculation mode on/off every few seconds, then Vista is happy and
lets Excel run as it does under XP.

Is there some way I can keep the automatic calculation turned off, and
yet keep touching Vista in some way that won't make Vista declare
Excel to have become unresponsive?

Thanks.

Bill