how to fix this Parser Error Message?

Server Error in '/ASPdotNET/ManagingData' Application.
--------------------------------------------------------------------------------

Configuration Error 
Description: 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: File or assembly name System.Web, or one of its dependencies, was not found.

Source Error: 


Line 71: -->
Line 72: <httpHandlers>
Line 73: <add verb="*" path="*.vb" type="System.Web.HttpNotFoundHandler,System.Web" />
Line 74: <add verb="*" path="*.cs" type="System.Web.HttpNotFoundHandler,System.Web" />
Line 75: <add verb="*" path="*.vbproj" type="System.Web.HttpNotFoundHandler,System.Web" />


Source File: c:\inetpub\wwwroot\ASPdotNET\ManagingData\web.conf  ig Line: 73 

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


=== Pre-bind state information ===
LOG: DisplayName = System.Web
(Partial)
LOG: Appbase = file:///c:/inetpub/wwwroot/ASPdotNET/ManagingData
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: System.Web
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Fr....4322/Temporary ASP.NET Files/aspdotnet_managingdata/b4ce0212/30cde314/System.Web.DLL.
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Fr....4322/Temporary ASP.NET Files/aspdotnet_managingdata/b4ce0212/30cde314/System.Web/System.Web.DLL.
LOG: Attempting download of new URL file:///c:/inetpub/wwwroot/ASPdotNE.../System.Web.DLL.
LOG: Attempting download of new URL file:///c:/inetpub/wwwroot/ASPdotNE.../System.Web.DLL.
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Fr....4322/Temporary ASP.NET Files/aspdotnet_managingdata/b4ce0212/30cde314/System.Web.EXE.
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Fr....4322/Temporary ASP.NET Files/aspdotnet_managingdata/b4ce0212/30cde314/System.Web/System.Web.EXE.
LOG: Attempting download of new URL file:///c:/inetpub/wwwroot/ASPdotNE.../System.Web.EXE.
LOG: Attempting download of new URL file:///c:/inetpub/wwwroot/ASPdotNE.../System.Web.EXE.

 


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