ASP.NET MVC4 Installer is incompatible with Microsoft .NET Framework 4.5Apparently, this was documented in the ASP.NET MVC4 installation notes.
This release is not compatible with the .NET Framework 4.5 Developer Preview. You must uninstall the .NET 4.5 Developer Preview before installing the ASP.NET MVC 4 Beta.I guess you have to be forgiving if you want to play with the early bits.
Make sure to uninstall all the .NET Framework 4.5 related stuff though. I had some pain, wasting over an hour, after only partially removing the installation.
Update: Brad Wilson answers the question why they aren't compatible.
Update: Scott Guthrie announced that the next Beta release should be compatible.