I got strange problem with my Visual Studio - yesterday I've installed the cumulative Windows 8 update described here
and then when I started Visual Studio I received message, that ReSharper plugin is broken and must be disabled. So i reinstalled it using the latest EAP v5. When starting Visual Studio ReSharper is now active, but it's just not working - all my referenced namespaces are in red, don't know what to do. This might be also related to strange issue I had yesterday with my PC when it gets stuck during the booting and I started the automated repair, maybe Visual Studio is broken somehow. Anyway the result is when I open my WP7 solution in VS2012, ReSharper is broken, all in red, but building and running my app in emulator works just fine.
I'll try the "Visual Studio repair" and let you know, if it helps.
Edit: finished Visual Studio repair, nothing has changed, namespaces and usings of my projects are still in red, altough building and running works just fine.