I am stuck. Why this exception occurs.
My Entire Server logs fills with the following error
'Unable to complete network request to host "" '
So that the DB queries failed. I read so many forums and got some clue that these errors are happening due to ANTI-Virus. I totally stopped the AV. Still i have this problem.

Stack Trace:
[08:21:53:512]|[03-20-2013]|[com.adventnet.netutils.fw.util.SchedulerTask]|[WARNING]|[15]: executeTask : Exception while executing scheduled task in |
org.firebirdsql.jdbc.FBSQLException: GDS Exception. 335544721. Unable to complete network request to host "".
Reason: Unable to complete network request to host "".
at org.firebirdsql.jdbc.InternalTransactionCoordinator$LocalTransactionCoordinator.ensureTransaction(InternalTransactionCoordinator.java:313)
at org.firebirdsql.jdbc.InternalTransactionCoordinator$LocalTransactionCoordinator.executionStarted(InternalTransactionCoordinator.java:342)
at org.firebirdsql.jdbc.InternalTransactionCoordinator.executionStarted(InternalTransactionCoordinator.java:38)
at org.firebirdsql.jdbc.AbstractStatement.notifyStatementStarted(AbstractStatement.java:235)
at org.firebirdsql.jdbc.AbstractStatement.notifyStatementStarted(AbstractStatement.java:226)
at org.firebirdsql.jdbc.AbstractStatement.executeQuery(AbstractStatement.java:208)
at org.jboss.resource.adapter.jdbc.WrappedStatement.executeQuery(WrappedStatement.java:250)
at com.adventnet.netutils.fw.util.SchedulerTask.getToolNameFromTask(SchedulerTask.java:80)
at com.adventnet.netutils.fw.util.SchedulerTask.executeTask(SchedulerTask.java:28)
at com.adventnet.taskengine.internal.SchedulerBean.executeTask(SchedulerBean.java:560)
at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.adventnet.mfw.bean.BeanProxy.invoke(BeanProxy.java:53)
at $Proxy2.executeTask(Unknown Source)
at com.adventnet.taskengine.internal.ScheduleExecutor.executeNextTask(ScheduleExecutor.java:147)
at com.adventnet.taskengine.internal.ScheduleExecutor.run(ScheduleExecutor.java:81)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
at org.firebirdsql.gds.GDSException: Unable to complete network request to host "".
at org.firebirdsql.gds.impl.wire.AbstractJavaGDSImpl.iscStartTransaction(AbstractJavaGDSImpl.java:737)
at org.firebirdsql.gds.impl.GDSHelper.startTransaction(GDSHelper.java:583)
at org.firebirdsql.jca.FBManagedConnection.findIscTrHandle(FBManagedConnection.java:1006)
at org.firebirdsql.jca.FBManagedConnection.internalStart(FBManagedConnection.java:925)
at org.firebirdsql.jca.FBLocalTransaction.internalBegin(FBLocalTransaction.java:140)
at org.firebirdsql.jca.FBLocalTransaction.begin(FBLocalTransaction.java:112)
at org.firebirdsql.jdbc.InternalTransactionCoordinator$LocalTransactionCoordinator.ensureTransaction(InternalTransactionCoordinator.java:311)
at org.firebirdsql.jdbc.InternalTransactionCoordinator$LocalTransactionCoordinator.executionStarted(InternalTransactionCoordinator.java:342)
at org.firebirdsql.jdbc.InternalTransactionCoordinator.executionStarted(InternalTransactionCoordinator.java:38)
at org.firebirdsql.jdbc.AbstractStatement.notifyStatementStarted(AbstractStatement.java:235)
at org.firebirdsql.jdbc.AbstractStatement.notifyStatementStarted(AbstractStatement.java:226)
at org.firebirdsql.jdbc.AbstractStatement.executeQuery(AbstractStatement.java:208)
at org.jboss.resource.adapter.jdbc.WrappedStatement.executeQuery(WrappedStatement.java:250)
at com.adventnet.netutils.fw.util.SchedulerTask.getToolNameFromTask(SchedulerTask.java:80)
at com.adventnet.netutils.fw.util.SchedulerTask.executeTask(SchedulerTask.java:28)
at com.adventnet.taskengine.internal.SchedulerBean.executeTask(SchedulerBean.java:560)
at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.adventnet.mfw.bean.BeanProxy.invoke(BeanProxy.java:53)
at $Proxy2.executeTask(Unknown Source)
at com.adventnet.taskengine.internal.ScheduleExecutor.executeNextTask(ScheduleExecutor.java:147)
at com.adventnet.taskengine.internal.ScheduleExecutor.run(ScheduleExecutor.java:81)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)