devenv /rebuild - strange message, help?

Getting the error "The application for project 'projectname' is not installed.

Make sure the application for the project type (.csproj) is installed.
Some of the properties associated with the solution could not be read.==========
Rebuild All: 0 succeeded, 0 failed, 1 skipped =========="

This occurs when I run a devenv command from the MS-DOS command prompt through a bat file. Im just trying to use the /rebuild command. It only comes up when I try to compile certain solutions. Other solutions of the same project type compile fine. If I open Visual Studios and compile, it works fine. If I /run instead of /rebuild, it works fine...

Any thoughts?