Friends, Thanks for the Reply.
Here are few details I found on the server.
Below are the tasks which are run by the NT Authority\System user in the server.
1.EXECUTE msdb.dbo.sp_sqlagent_get_perf_counters - SQL Agent Alert Engine
2.SELECT ISNULL(SUSER_SNAME(), SUSER_NAME()) - SQL Agent EMail Logger
3.UPDATE msdb.dbo.sysjobactivity - SQL Agent Job Invocation Engine
4.msdb.dbo.sysmail_help_admin_account_sp;1 - SQL Agent90 - id <2764>
I suspect on the No.1 task which could cause the issue,since it is batched every minute when checked in the Activity Monitor.But not sure on what way its affecting.
Thanks in advance