Login failed for "user" in ssis

[Load_Row table [9928]] Error: SSIS Error Code DTS_E_CANNOTACQUIRECONNECTIONFROMCONNECTIONMANAGER.  
The AcquireConnection method call to the connection manager "DB_NAME" failed with error code 0xC0202009.  
There may be error messages posted before this with more information on why the AcquireConnection method call failed.

[SSIS.Pipeline] Error: component "Load_Row table" (9928) failed validation and returned error code 0xC020801C.

[Connection manager "Raven_MSSQL"] Error: SSIS Error Code DTS_E_OLEDBERROR.  An OLE DB error has occurred. Error code: 0x80040E4D.
An OLE DB record is available.  Source: "Microsoft SQL Server Native Client 10.0"  Hresult: 0x80040E4D  Description: "Login failed for user '****'."

I am getting above error for 10-12 packages in my pre-prod environment .

But Couple of week before, It was fine and loaded the data.

I have checked the config files and could see no changes happened and everything looks same.But when I downloaded the same package from server and executed, i got the same error.After google, I changed the protection level and executed, it got succeeded.

Do I want to change the protection level and re-deploy ?

Please put your suggestion which helps me to overcome this issue.

Thanks in advance