I downloaded Visual Studio 2015 CTP Preview because I wanted to test to see if I could load in a Roslyn Code Issue extension.
When I try to create a simple console application using New Project -> Console Aplication I am getting the following error dialog.

Any ideas what might be causing this? I have reinstalled and same issue.
I had the same problem and found the solution on another site. Here are the steps that need to be performed:
cd C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE
devenv /installvstemplates