You get this error when attempting to run your 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: Access is denied: 'BaseClasses'.
This error is caused when the Microsoft Indexing Service on your system is currently indexing one of your application’s files. Microsoft found a problem where files are getting locked and not released (in time).
Disable Microsoft Indexing Service and set it to manual so it does not auto-start again. Alternatively, if you want to use the Indexing Service, then go to the Microsoft Management Console and expand "Services and Applications" then "Indexing Service" ->System ->Directories. In the directories, you can explicitly add:
C:\WINNT\Microsoft.NET\Framework\ v1.1.4322\Temporary ASP.NET Files
...and set it NOT to be indexed.
Two possible resolutions are described in Microsoft knowledge base article 329065:
http://support.microsoft.com/default.aspx?scid=kb;en-us;329065
Part VII: Troubleshooting Applications
Application Runs But No Data is Displayed