Question about async calls to wcf services

[ksen]

I am calling wcf service asynchronously, It works fine most of the time.
Sometimes i get exceptions. When i see the event log there are few event
logs related to the async calls. Could some one explain what this about and
how to correct it.?

Here is the event details:

Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 10/24/2006 2:30:19 PM
Event time (UTC): 10/24/2006 9:30:19 PM
Event ID: a8354ce8635347e1a467cac69922ac9e
Event sequence: 74
Event occurrence: 1
Event detail code: 0

Application information:
Application domain: /LM/W3SVC/2/Root-1-128061983222921200
Trust level: Full
Application Virtual Path: /
Application Path: C:\trunk\\dev\src\
Machine name: machine1

Process information:
Process ID: 5420
Process name: w3wp.exe
Account name: NT AUTHORITY\NETWORK SERVICE

Exception information:
Exception type: HttpException
Exception message: Exception of type 'System.Web.HttpException' was
thrown.

Request information:
Request URL:
https://localhost/Patients/PHR/Provi...fo.aspx?ptid=2
Request path: /Patients/PHR/ProviderViewMedicalInfo.aspx
User host address: 127.0.0.1
User:
Is authenticated: False
Authentication Type:
Thread account name: NT AUTHORITY\NETWORK SERVICE

Thread information:
Thread ID: 15
Thread account name: NT AUTHORITY\NETWORK SERVICE
Is impersonating: False
Stack trace: at System.Web.HttpAsyncResult.End()
at System.Web.UI.PageAsyncTaskManager.EndExecuteAsync Tasks(IAsyncResult ar)
at System.Web.UI.Page.PageAsyncInfo.OnAsyncHandlerCom pletion(IAsyncResult
ar)
Custom event details:

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.

Thanks