When setting a friendly URL name, you must bear in mind that your page name should end in .aspx extension unless you set wildcard application mapping. In IIS version 5.x you can do this by adding a new application map:
1. from your project click Properties, go to the virtual folder tab and click Configuration
2. in the executable textbox place the path to the aspnet_isapi.dll
3. in the extension textbox you must specify the ".*
" to specify all kinds of extension.
Also make sure that the "Check that file exist" checkbox is unchecked. In IIS 6 you will only need to specify the path to the aspnet_isapi.dll executable through the wildcard application maps list.
When you are creating your friendly names make sure that this url does not exist anywhere else in your project. If the url exists, you will get the Violation error you sent us.