ReportViewer Session Expired error

[Jeje]

Him

I know a lot of people suffer this issue in the past...
but in my case it's really hard to reproduce the session timeout error.
everything works fine, the user can see the reports etc...

this can works fine for days.
and suddenly a user can receive the timeout error, and only when he try to
export the report! (in PDF or Excel...)
if the user purge his internet explorer cache and export again, then it's
ok.

I have changed the expiration in IIS and in the web.config to 1 hour.
But the user come back few days later and the error is raised again!

the control is displayed in a page which is in a popup page and through an
IFrame
Popuppage -> HTML page -> IFrame -> ASPX page -> Reportviewer
but also I have tried this:
Popuppage -> HTML page -> FrameSet -> ASPX page -> Reportviewer

I add a timestamp in the HTML page and the ASPX pages
/reports/viewreport.html?t=<timestamp>
/reports/runreport.aspx?t=<timestamp>&other parameters...

So this insure that IE don't cache the pages, but the error still here!!!!!

I'm out of ideas and the error is really random and only when I export.
The SP1 of the reportviewer control is applied.

Thanks for your help if anybody know how to solve this.

Jerome.

 

[Jeje]

oups... sorry for the cross posting.