What causes ####### to display into infinity. I know normally when this
happens it means the column width is not correct, but what I am getting is
one that auto colmn resizing has no effect on.

The cell causing the problem is E5 it is formatted Custom h:mm with the
formula =D4-C5

D5 and C5 is formatted General and when a value is entered such as 845 it
changes to 8:45:00 AM with a fomat of Custom h:mm:ss AM/PM

I do not want the formatting of D5 or C5 to be altered as it is very
convient to enter 845 to display the time for example.

Anyone got some idea what is happening here.