Session state error when connecting from bdc to infopath

[Nathan]

Hi I get the following error, when connecting from my bdc web part to an
infopath form. The bdc passes a parameter to the infopath codebehind form,
which then in turn passes this parameter to a web service. The web service
then retrieves values from the db and fills out the fields of the form. This
error only occurs during the first usage of the bdc to connect to the form.
Subsequent uses work fine.
Any ideas.
Thanks.

Session state has created a session id, but cannot save it because the
response was already flushed by the application. at
System.Web.SessionState.SessionIDManager.SaveSessionID(HttpContext context,
String id, Boolean& redirected, Boolean& cookieAdded)
at System.Web.SessionState.SessionStateModule.CreateSessionId()
at System.Web.SessionState.SessionStateModule.DelayedGetSessionId()
at System.Web.SessionState.SessionStateModule.OnReleaseState(Object
source, EventArgs eventArgs)
at
System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&
completedSynchronously)