This situation happens when Pivotier attempts to display the last date of a fiscal year. The reason 12/31/9999 is displayed is because the next fiscal year has not been created in Accounting Periods in NAV.
The solution is to create the next fiscal year in Accounting Periods in NAV. To do this:
1) Go to Financial Management of your NAV solution
2) Select Periodic Activities, then Fiscal Year
3) In the Fiscal Year page, select Accounting Periods. The Accounting Periods table should open in the working window.
4) From the Accounting Periods table select the Create Year button. This will produce a new fiscal year in your NAV solution and you should be able to run your Pivotier Financial Reports without the 12/31/9999 problem.