Logon failure: unknown user name or bad password.

hi,
i go the bellow error please help me how to reslove it.

Logon failure: unknown user name or bad password.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IO.IOException: Logon failure: unknown user name or bad password.


Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace:


[IOException: Logon failure: unknown user name or bad password.
]
   System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +7714920
   System.IO.File.InternalCopy(String sourceFileName, String destFileName, Bo ...