Visual Studio 2010项目将不会调试 - 错误14无法将“ItemTypes”类型的对象强制转换为“System.String”类型

I am helping another developer with his .net application and he told me when he installed visual studio 2012 on his machine it messed up his vs2010 application. When I try to debug or build my website which is web forms .net 3.5 I get these errors:I am helping another developer with his .net ap