The default behavior of Windows 2000 is to limit the maximum run time of a scheduled task to 72 hour.
Starting with Service Pack 3, you may alter this timeframe:
1. Use the Registry Editor to navigate to:
2. Edit or add a AtTaskMaxHours Value Name, a REG_DWORD data type, and set the data value to 0 to disable the maximum time, or to a number between 1 and 999 hours.
3. Shutdown and restart Windows 2000.