I am trying to close a task through a sharepoint timer job using the service account. But there's an authentication issue in one of the servers of my FARM in which K2 is present. Can someone please help me in solvin this issue.

Following is the stack trace of the exception that got logged in K2 logs.

01:35:33","Debug","Unknown","8039","ReceiveBytes","SourceCode.Workflow.Runtime.ClientConnection.ProcessICOPEvent","8039 Receiving xx.xx.xxx.xxxx:xxxx Bytes From 700","anonymous","0.0.0.0","xxxxxxxs001:C:Program Files (x86)K2 blackpearlHost ServerBin","148301637","7c27da0690a843279eba4b8de36cbbc4",""
"148301638","2013-08-08
01:35:33","Error","SystemAudit","24404","AuthUserFail","K2Worker.AuthNative","24404 Authentication with server failed for xxxx_xxx_xx_Service@<DOMAIN>.US.NAM.AD.xxxxxxx.COM with Message: AcceptSecurityContext failed: The logon attempt failed
","anonymous","0.0.0.0","xxxxxxxxxx001:C:Program Files (x86)K2 blackpearlHost ServerBin","148301638","e3de7bf443e741fd9cc268ffe1db0874",""
"148301639","2013-08-08

Note: The same code works fine when put in a custom webpart. the only difference I see is that webparts runs on W3p.exe and Timer job on OwSTIMER.exe.