Crystal Reports why 'Thread is being aborted'

Message

   Hi I use crystal report 11 which is integrated into asp.net2.0 web page.

the report use 3 very large views from oracle and contains 3 subreports.

It generates around 600 pages of report data. some times while exporting the report to PDF i get "The thread is being aborted" .

For ur information it takes around 8 minutes to generate the report. and my session time out is way beyond this limit which is more then half an hour. The size of the report in PDF is around 700 kb.

i have hundreds of other reports using the same report viewer page but none of them show such anomaly.

Here is the code  :-
------------------------------------------------------

MemoryStream ostream = new MemoryStream();

ostream = (MemoryStream)rptDoc.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);

Response.Clear();
Response.Buffer = true;

Response.ContentType = "application/pdf";

Response.BinaryWrite(ostream.ToArray());
ostream.Close();
ostream.Dispose();
GC.Collect();

Response.End();
--------------------------------------

what is the reason ? Any help is appreciated.

Thanks & Regards...
Deb