Crazy! Microsoft Enterprise Library configuration problems !!!

Configuration Error

Note:An error occurred while processing the configuration file required to provide services to the request. Check the following error details and modify the configuration file as appropriate.

Analyzer error message:An error occurred while creating the dataconfiguration configuration section handler: failed to load the file or assembly "Microsoft. practices. enterpriselibrary. data, version = 3.1.0.0, culture = neutral, publickeytoken = b03f5f7f11d50a3a "or one of its dependencies. The Assembly list definition found does not match the Assembly reference. (Exception from hresult: 0x80131040)

Source error:

Row 10: <configuration> row 11: <configsections> row 12: <section name = "dataconfiguration" type = "Microsoft. practices. enterpriselibrary. data. configuration. databasesettings, Microsoft. practices. enterpriselibrary. data, version = 3.1.0.0, culture = neutral, publickeytoken = b03f5f7f11d50a3a "/> row 13: </configsections> row 14: <appsettings/>

Source file:E: \ system file \ My Documents \ Visual Studio 2005 \ websites \ WEB. configRow:12

Assembly loading tracking:The following information helps determine why the assembly "Microsoft. Practices. enterpriselibrary. Data, version = 3.1.0.0, culture = neutral, publickeytoken = b03f5f7f11d50a3a" cannot be loaded.

Warning assembly binding logging is disabled. To enable the Assembly Binding failure log, set the registry value to [HKLM \ Software \ Microsoft \ Fusion! Enablelog] (DWORD) is set to 1. Note: There will be some performance loss associated with the Assembly Binding failure log. To disable this function, remove the registry value [HKLM \ Software \ Microsoft \ Fusion! Enablelog].

One of my solutions: Change publickeytoken = b03f5f7f11d50a3a in webconfig
Publickeytoken = NULL
Note that there are other issues to be changed. In addition to this issue, please google!