.isproj无法打开，因为它的项目类型（.isproj）不受支持

I've got 2 VS 2008 based solutions I'm opening up and both have projects that are .NET 3.5. But when I open both solutions in VS 2008, both have some .isproj file(s) and I get this stupid error right after I open the solution:I've got 2 VS 2008 based solutions I'm opening