>>I'm not upgrading my existing SQL Server 2008 R2, I want to install SQL Server 2012 as a new instance and switch between them at will.
>
>Is your SQL2012 the eval edition or a licensed edition? If your MSDN has expired, I'm assuming it is the eval?
>
>If not and this is a version you paid outright for, I'd make a product support call to Microsoft and have them figure out what is wrong with their installer. Being their problem (which I'm confident it is) they should waive any fee for the support.
>
>Reading this thread and the msdn thread it's pretty obvious this is another screwed installer that Microsoft has rushed out the door. You're being used as a beta tester at this point.

I got SQL Server 2012 Developer Edition CD sent to me from work by our Network Admin (so it is fully licensed). I installed VS 2010 Ultimate edition when I had MSDN Ultimate subscription which was given to me by a friend (he got 3 free subscriptions as MVP benefit).

We have MSDN subscription at work, but not Ultimate (I guess Professional).

I'm thinking that this particular scenario (when I have VS 2010 Ultimate installed and trying now to install SQL Server 2012 Developer) from removable media was never fully tested.