MetaData class can't be loaded and failed to load window layout

Hi,

Got some problems with a Unity project. My friend saved the project and it works fine for him, but when I'm trying to open it i get a popup saying "Failed to load window layout". With the options "Load default Layout", "Quit" and "Revert Factory Settings".

Now if i pick Load default Layout unity opens, but the Hierarchy is completely empty (meaning no game objects on the scene). If i go to the Unity console, there's a couple of messages about MetaData which can't be loaded etc.. Looks like this: http://i.imgur.com/CsshNA9.png

We are are both using latest version of Unity, but I'm on a PC and hes on Mac (if that has any meaning). And he can open the project, but not me.

Anyone know why this occurs? And if there is any way to fix it?

I'm very grateful for any help!