Hi! Please explain what is the cause of the following error? Thank you!

using K2 Blackpearl on a Standalone server with Windows 2008 and Sql Server 2008 latest updates:

This errors appears after logging on to a K2 workspace web site!

Error:

Log Name:      Application
Source:        ASP.NET 2.0.50727.0
Date:          2/16/2010 12:38:13 PM
Event ID:      1309
Task Category: Web Event
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      FHA-VPC001-GG.developer.vpc.fraserhealth.org
Description:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 2/16/2010 12:38:12 PM
Event time (UTC): 2/16/2010 8:38:12 PM
Event ID: f0cb2a5ec8274883a16add30fa43c623
Event sequence: 56
Event occurrence: 1
Event detail code: 0
 
Application information:
    Application domain: /LM/W3SVC/3/ROOT/Workspace-1-129108260546385840
    Trust level: Full
    Application Virtual Path: /Workspace
    Application Path: c:program filesk2 blackpearlWorkspaceSite
    Machine name: FHA-VPC001-GG
 
Process information:
    Process ID: 2504
    Process name: w3wp.exe
    Account name: DEVELOPERk2worker
 
Exception information:
    Exception type: SoapException
    Exception message: System.Web.Services.Protocols.SoapException: Execution 'xm1u1tbcfbyqclvr3cfu3h55' cannot be found ---> Microsoft.ReportingServices.Diagnostics.Utilities.ExecutionNotFoundException: Execution 'xm1u1tbcfbyqclvr3cfu3h55' cannot be found
   at Microsoft.ReportingServices.WebServer.ReportExecution2005Impl.GetExecutionInfo(ExecutionInfo2& executionInfo)
   at Microsoft.ReportingServices.WebServer.ReportExecutionService.GetExecutionInfo(ExecutionInfo& executionInfo)
 
Request information:
    Request URL: http://k2host/Workspace/Reserved.ReportViewerWebControl.axd?ReportSession=xm1u1tbcfbyqclvr3cfu3h55&ControlID=6adb6c0482424a25ae3f8507dc14afac&Culture=1033&UICulture=1033&ReportStack=1&OpType=SessionKeepAlive&TimerMethod=KeepAliveMethodctl07_ctl00TouchSession0&CacheSeed=Tuehttp://k2host/Workspace/Reserved.ReportViewerWebControl.axd?ReportSession=xm1u1tbcfbyqclvr3cfu3h55&ControlID=6adb6c0482424a25ae3f8507dc14afac&Culture=1033&UICulture=1033&ReportStack=1&OpType=SessionKeepAlive&TimerMethod=KeepAliveMethodctl07_ctl00TouchSession0&CacheSeed=Tuehttp://k2host/Workspace/Reserved.ReportViewerWebControl.axd?ReportSession=xm1u1tbcfbyqclvr3cfu3h55&ControlID=6adb6c0482424a25ae3f8507dc14afac&Culture=1033&UICulture=1033&ReportStack=1&OpType=SessionKeepAlive&TimerMethod=KeepAliveMethodctl07_ctl00TouchSession0&CacheSeed=Tuehttp://k2host/Workspace/Reserved.ReportViewerWebControl.axd?ReportSession=xm1u1tbcfbyqclvr3cfu3h55&ControlID=6adb6c0482424a25ae3f8507dc14afac&Culture=1033&UICulture=1033&ReportStack=1&OpType=SessionKeepAlive&TimerMethod=KeepAliveMethodctl07_ctl00TouchSession0&CacheSeed=Tue%20Feb%2016%2012%3A37%3A16%202010Feb%2016%2012%3A37%3A16%202010Feb%2016%2012%3A37%3A16%202010Feb%2016%2012%3A37%3A16%202010
    Request path: /Workspace/Reserved.ReportViewerWebControl.axd
    User host address: 192.18.1.101
    User: DEVELOPERAdministrator
    Is authenticated: True
    Authentication Type: Negotiate
    Thread account name: DEVELOPERk2worker
 
Thread information:
    Thread ID: 3
    Thread account name: DEVELOPERk2worker
    Is impersonating: True
    Stack trace:    at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Objectp] parameters)
   at Microsoft.SqlServer.ReportingServices2005.Execution.ReportExecutionService.GetExecutionInfo()
   at Microsoft.SqlServer.ReportingServices2005.Execution.RSExecutionConnection.GetExecutionInfo()
   at Microsoft.Reporting.WebForms.ServerReport.TouchSession()
   at Microsoft.Reporting.WebForms.SessionKeepAliveOperation.PerformOperation(NameValueCollection urlQuery, HttpResponse response)
   at Microsoft.Reporting.WebForms.HttpHandler.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
 
 
Custom event details:

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="ASP.NET 2.0.50727.0" />
    <EventID Qualifiers="32768">1309</EventID>
    <Level>3</Level>
    <Task>3</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2010-02-16T20:38:13.000Z" />
    <EventRecordID>33182</EventRecordID>
    <Channel>Application</Channel>
    <Computer>FHA-VPC001-GG.developer.vpc.fraserhealth.org</Computer>
    <Security />
  </System>
  <EventData>
    <Data>3005</Data>
    <Data>An unhandled exception has occurred.</Data>
    <Data>2/16/2010 12:38:12 PM</Data>
    <Data>2/16/2010 8:38:12 PM</Data>
    <Data>f0cb2a5ec8274883a16add30fa43c623</Data>
    <Data>56</Data>
    <Data>1</Data>
    <Data>0</Data>
    <Data>/LM/W3SVC/3/ROOT/Workspace-1-129108260546385840</Data>
    <Data>Full</Data>
    <Data>/Workspace</Data>
    <Data>c:program filesk2 blackpearlWorkspaceSite</Data>
    <Data>FHA-VPC001-GG</Data>
    <Data>
    </Data>
    <Data>2504</Data>
    <Data>w3wp.exe</Data>
    <Data>DEVELOPERk2worker</Data>
    <Data>SoapException</Data>
    <Data>System.Web.Services.Protocols.SoapException: Execution 'xm1u1tbcfbyqclvr3cfu3h55' cannot be found ---&gt; Microsoft.ReportingServices.Diagnostics.Utilities.ExecutionNotFoundException: Execution 'xm1u1tbcfbyqclvr3cfu3h55' cannot be found
   at Microsoft.ReportingServices.WebServer.ReportExecution2005Impl.GetExecutionInfo(ExecutionInfo2&amp; executionInfo)
   at Microsoft.ReportingServices.WebServer.ReportExecutionService.GetExecutionInfo(ExecutionInfo&amp; executionInfo)</Data>
    <Data>http://k2host/Workspace/Reserved.ReportViewerWebControl.axd?ReportSession=xm1u1tbcfbyqclvr3cfu3h55&amp;ControlID=6adb6c0482424a25ae3f8507dc14afac&amp;Culture=1033&amp;UICulture=1033&amp;ReportStack=1&amp;OpType=SessionKeepAlive&amp;TimerMethod=KeepAliveMethodctl07_ctl00TouchSession0&amp;CacheSeed=Tue%20Feb%2016%2012%3A37%3A16%202010</Data>
    <Data>/Workspace/Reserved.ReportViewerWebControl.axd</Data>
    <Data>192.18.1.101</Data>
    <Data>DEVELOPERAdministrator</Data>
    <Data>True</Data>
    <Data>Negotiate</Data>
    <Data>DEVELOPERk2worker</Data>
    <Data>3</Data>
    <Data>DEVELOPERk2worker</Data>
    <Data>True</Data>
    <Data>   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, ObjectÂ] parameters)
   at Microsoft.SqlServer.ReportingServices2005.Execution.ReportExecutionService.GetExecutionInfo()
   at Microsoft.SqlServer.ReportingServices2005.Execution.RSExecutionConnection.GetExecutionInfo()
   at Microsoft.Reporting.WebForms.ServerReport.TouchSession()
   at Microsoft.Reporting.WebForms.SessionKeepAliveOperation.PerformOperation(NameValueCollection urlQuery, HttpResponse response)
   at Microsoft.Reporting.WebForms.HttpHandler.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)
</Data>
  </EventData>
</Event>