Export Crystal Report into PDF In Firefox (Urgent)

Hi all,
A popup window has been used to print report in PDF format. Popup window calls as follows.

string url = "LoanInstallmentsReport.aspx?year=" + txtYear.Text + "&month=" + ddlMonth.SelectedValue;
ScriptManager.RegisterStartupScript(Page, this.GetType(), "newWindow", string.Format("<script>window.open('{0}');</script>", url), true);
This code opens popup in both IE and FireFox.

Following code used to generate PDF in page load even in popup window.
CrystalReportViewer1.ReportSource = _rdEstimation;

//Exporting PDF
MemoryStream oStream; // using System.IO
oStream = (MemoryStream)
Response.Buffer = true;
Response.ContentType = "application/pdf";

It create PDF in IE but firefox not.
Any solution.