I have Given all permission, Also referrenced them in my project

I get this type of error for different different dll some time for nunit.framework,some time for Nant.core. And sometime projects run successfully after rebuilding. Unable to understand the cause of the problem

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An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Access is denied: 'NHibernate.Tasks'.

Source Error:


Line 197: <add assembly="System.EnterpriseServices, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 198: <add assembly="System.Web.Mobile, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 199: <add assembly="*"/>
Line 200: </assemblies>
Line 201: </compilation>


Source File: c:\windows\microsoft.net\framework\v1.1.4322\Config\machine.config Line: 199

Assembly Load Trace: The following information can be helpful to determine why the assembly 'NHibernate.Tasks' could not be loaded.


=== Pre-bind state information ===
LOG: DisplayName = NHibernate.Tasks
(Partial)
LOG: Appbase = file:///c:/inetpub/wwwroot/TrialHibernate
LOG: Initial PrivatePath = bin
Calling assembly : (Unknown).
===

LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Post-policy reference: NHibernate.Tasks
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/trialhibernate/7a7a734c/f0a28ba7/NHibernate.Tasks.DLL.
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/trialhibernate/7a7a734c/f0a28ba7/NHibernate.Tasks/NHibernate.Tasks.DLL.
LOG: Attempting download of new URL file:///c:/inetpub/wwwroot/TrialHibernate/bin/NHibernate.Tasks.DLL.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Post-policy reference: NHibernate.Tasks, Version=1.2.0.2003, Culture=neutral, PublicKeyToken=null




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Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573