Access Denied while loading Crystal Report

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C#

ASP.NET

Here is the error we are getting when trying
to use CrystalReportViewer with IIS....
but it works fine in development environment.......

OS: XP sp2 ASP.NET 2008
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Problem occurs when loading .rpt file...
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Server Error in '/Production' Application.
Access is denied.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Runtime.InteropServices.COMException: Access is denied.

Source Error:

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