Report timing out on website

Hi

I have a report that has been running fine up until last week when users started to experience timeouts when running the report. The incident happens at intermittent times of the day with some days the report runs fine.
The report is a RDLC file which is called through our asp.net website

Timeout set in webconfig is:

<!-- set the timeout of report viewer, value is in miliseconds-->
    <add key="ReportViewerTimeOut" value="6000000"/>

SQL time out is set at:

(Server properties\Connections)

remote server connections

remote Query time  out (in seconds. 0=no timeout)

750


After investigate HTTPERR logs, IIS logs and Event viewer i noticed the following events


IIS:

013-05-21 09:47:05 GET /Reports/PerformanceViewer.aspx Report=PerformanceReport&location_chooser_filter=Henley+Thames&location_chooser_location_type_id=1&location_chooser_sub_location_type_id=-1&location_chooser_id=16&location_filter_type=Depot&location_filter_type_id=1&SearchFilters.startDate=21%2F05%2F2013 - 127.0.0.1 Mozilla/4.0+(compatible;+MSIE+8.0;+Windows+NT+5.2;+Trident/4.0;+POIE4SP2;+.NET+CLR+1.1.4322;+.NET+CLR+2.0.50727;+.NET+CLR+3.0.4506.2152;+.NET+CLR+3.5.30729;+.NET4.0C;+.NET4.0E) http://localhost/Reports/MyReport/PerformanceReport localhost 500 0 10349 1119 60875

500 0 looks like a status and substatus error

HTTPERR:
Date                                IP              Port
2013-05-21 09:57:31 10.xx.xx.xx  1959 172.xx.xxx.x 443 - - - - - Timer_ConnectionIdle -
2013-05-21 09:57:31 10.xx.xx.xx 1961 172.xx.xxx.x 443 - - - - - Timer_ConnectionIdle -
2013-05-21 09:57:31 10.xx.xx.xx 1962 172.xx.xxx.x 443 - - - - - Timer_ConnectionIdle -
2013-05-21 09:57:37 10.xx.xx.xx 1962 172.xx.xxx.x 443 - - - - - Timer_ConnectionIdle -


(seems fine to me)

Event viewer:
Event Type:      Warning
Event Source:      ASP.NET 4.0.30319.0
Event Category:      Web Event
Event ID:      1309
Date:            21/05/2013
Time:            10:47:05
User:            N/A
Computer:      IISServer
Description:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 21/05/2013 10:47:05
Event time (UTC): 21/05/2013 09:47:05
Event ID: 92222d6976124410b2f73149b04e2f13
Event sequence: 95472
Event occurrence: 42
Event detail code: 0
 
Application information:
    Application domain: /LM
    Trust level: Full
    Application Virtual Path: /
    Application Path: C:\Program Files\Web\
    Machine name: IISServer
 
Process information:
    Process ID: 20176
    Process name: w3wp.exe
    Account name: IISServer\svcBWe
 
Exception information:
    Exception type: HttpUnhandledException
    Exception message: Exception of type 'System.Web.HttpUnhandledException' was thrown.
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.Util.AspCompatApplicationStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.


I have ran the query on the SQL server and it runs first time 22 seconds then under 2 seconds atter that. But on the website its timing out everytime.

Im wondering it IIS is the problem here? Is there any checks i can do in IIS6 other than increasing timeout?