Tod1d's Thought Process

This error drove me nuts for the longest time. You have been unit testing your project. After your n-th time rebuilding, you call the .aspx page you are trying to test and you get an error similar to this one:

Configuration Error

Parser Error Message: Access is denied:

Source Error:
Line 196: <add assembly="System.EnterpriseServices, Version=1.0.5000.0,
Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">

Line 197: <add assembly="System.Web.Mobile, Version=1.0.5000.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a">

Line 198: <add assembly="*">

This error drove me nuts for the longest time. I would end up closing Visual Studio .NET and restart IIS. This would usually solve the problem for a short time.

Solution:
Stop the Indexing Service. Apparently the Indexing Service can hold a lock on the temporary ASP.NET files directory for one to five minutes (depending on the size of the directory).

To stop the Indexing Service in Windows XP you can do the following :
1. Click Start -> Control Panel -> Administrative Tools -> Computer Management -> Services and Applications.
2. Right-click Indexing Service.
3. Click "stop".

Enjoy.