出现CS0016的原因一般是临时目录的权限不够，至于为什么中途出现这种问题，我尚不清楚，解决的办法是给Windows目录下的临时文件夹Temp的安全选项卡中加入NetWork Service用户并赋予全权。更详尽的解释参考MSDN。
MSDN给出的解释如下：
When you view a Microsoft ASP.NET Application in a Web browser, you may receive the following error messages:
For the Microsoft .NET Framework version 1.1, the error message is the following:
CS0016: Could not write to output file 'c:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\Temporary ASP.NET Files\application1\c11b43f6\cf3ec03\rizcntet.dll' . The directory name is invalid.
For the .NET Framework 1.0, the error message is the following:
CS0013: Unexpected error writing metadata to file 'C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\Temporary ASP.NET Files\application2\3fc72f26\eb731247\ev2bslce.dll'. The directory name is invalid.
CAUSE
The system TEMP and TMP variables point to a folder that does not exist. The compiler generates temporary files in the folder where the TEMP and the TMP variables point to before the files are copied to the Temporary ASP.NET Files folder. However, the folder where the system variables point to is deleted when you restart the computer. Therefore, the compiler cannot generate the temporary files.
RESOLUTION
1. Create a temporary folder under %Systemroot%, and then name it Temp.
2. Grant full permissions on the Temp folder to the aspnet user account in .NET Framework 1.0 or to the NETWORK SERVICE user account in .NET Framework 1.1.
3. Right-click My Computer, and then click Properties.
4. On the Advanced tab, click Environment Variables.
5. Select the TEMP variable under System variables, and then click Edit.
6. Type %SystemRoot%\TEMP in the Variable Value box, and then click OK.
7. Repeat steps 5 and 6 to edit the TMP variable. Click OK two times.
8. Click Start, and then click Run.
9. To reset Internet Information Services (IIS), type iisreset on the command prompt.
Note If the error message that is mentioned in the "Symptoms" section of this article persists, restart the computer.