In Excel 2000, I have used a spreadsheet for over 9 months without issue.

All of a sudden, the GETPIVOTDATA function returns #N/A for 75% of its use,
working normally for the other 25%.

The pivot table, and its underlying data, changes every day to the extent
that another day's transactions appear at the right-hand side of the pivot
data. The incremental label is a date; the analysis labels remain unchanged.

Why has GETPIVOTDATA sudden gone inconsistently stupid and what is the
solution?