出现这个问题是由于Silverlight 3 Tools异常造成的。请先卸载Silverlight 3 Tools,然后重新安装即可。
英文版:
http://www.microsoft.com/Downloads/details.aspx?familyid=9442B0F2-7465-417A-88F3-5E7B5409E9DD&displaylang=en
中文版:
http://www.microsoft.com/Downloads/details.aspx?familyid=9442B0F2-7465-417A-88F3-5E7B5409E9DD&displaylang=zh-cn