Visual Studio 2005: "The Directory Name is Invalid(目录名称不正确)" Error
Visual Studio 2005: "Failed to find definition" Error
Description
When working with a Web Site project in Visual Studio 2005 you may get an error when re-naming control ID in design mode.
Error message can be one of the following:
1.Failed to find definition.
2.The directory name is invalid.
The error may not happen if you don't have App_Code directory defined within your project.
Workaround
1. Navigate to the directory(找到以下路径,为你的主机名) ..\Documents and Settings\\Local Settings\Application Data\Microsoft\WebsiteCache
2. Create a folder with the same name as the name of your project. (在刚才的WebsiteCache目录下查找以你工程名称的文件夹,若没有就以你当前报错的工程名称添加一个文件夹，若已存在请清空文件夹内容
摘自：http://blog.csdn.net/xcjwxx/archive/2007/08/29/1763963.aspx