Reg : Error CNC-SDS-0413 ( user Authentication failed )

[chalapathi]

Hi Friends   
              I have 3 reports contains in a Specific folder,The design of the reports are like  Each user can schedule these reports individually , i have admin priviliges i observed that last 4 days onwards  these all schedules are failing ,i am getting error below for all users who are scheduling these 3 reports ,i tried in google i got solution is Renew the pass word,if it fails for any particular user we can do that, but these 3 repots failing for all users

CNC-SDS-0413 There was a problem in executing the task. The user authentication failed. It may not be possible to rerun the task 
please help me on this issue Thanks in advance...............