I had a similar problem. I believe it is a conflict/mix-up in the registry between the pre PBP3 code studio and the post PBP3 code studio.

Here is what I did:
Uninstalled all versions of the code studio.
Ran regedit and searched for terms such as codestudio.exe, pbp.
Deleted registry entries related to these installations.
Reinstalled the PBP3 version of code studio.

That cleared up the mix-up.

You can really mess things up fiddling with the registry, so I don't recommend you take this route unless you are confident with what you are doing.
However, if you do this, please BACKUP YOUR REGISTRY!