Error in report server

I have just installed sql server 2005 developer edition with ssrs

I am getting following error

When Browsing

http://localhost/ReportServer$Yukon/
Reporting Services Error
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The permissions granted to user 'KAMRANSHAHID\IUSR_KAMRANSHAHID' are insufficient for performing this operation. (rsAccessDenied) Get Online Help

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SQL Server Reporting Services

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When editing Surface Area Configuration

TITLE: Surface Area Configuration

System.Web.Services.Protocols.SoapException: The permissions granted to user 'KAMRANSHAHID\IUSR_KAMRANSHAHID' are insufficient for performing this operation. > Microsoft.ReportingServices.Diagnostics.Utilities.AccessDeniedException: The permissions granted to user 'KAMRANSHAHID\IUSR_KAMRANSHAHID' are insufficient for performing this operation.
at Microsoft.ReportingServices.Library.RSService.SetSystemProperties(Property[] properties)
at Microsoft.ReportingServices.WebServer.ReportingService.SetSystemProperties(Property[] Properties)
End of inner exception stack trace
at Microsoft.ReportingServices.WebServer.ReportingService.SetSystemProperties(Property[] Properties) (System.Web.Services)

BUTTONS:

OK

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Also When I connect from management studio for the reporting services instance I get the same error of insufficient privilge

TITLE: Microsoft SQL Server Management Studio

Failed to retrieve data for this request. (Microsoft.SqlServer.SmoEnum)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&LinkId=20476

ADDITIONAL INFORMATION:

The permissions granted to user 'KAMRANSHAHID\IUSR_KAMRANSHAHID' are insufficient for performing this operation. (rsAccessDenied) (Report Services SOAP Proxy Source)

For help, click: http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsAccessDenied&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=9.00.1399.00

The permissions granted to user 'KAMRANSHAHID\IUSR_KAMRANSHAHID' are insufficient for performing this operation. (rsAccessDenied) (ReportingServicesLibrary)

For help, click: http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsAccessDenied&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=9.00.1399.00

BUTTONS:

OK

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What Am I missing ?

But While browsing report {not server } works fine

http://localhost/Reports$Yukon/Pages/Folder.aspx

SQL Server Reporting Services Home Home | My Subscriptions | Help

I have done by giving ntfs permission to user kamran shahid
and change ownership from administrator to kamranshahid
Now Only problem i am having is that when ever I browse for the reportmanager or reportserver the authentication window come up
in which i have to give my user name and password of the windows
How Can i get rid of this authentication window