Interface not registered (Exception from HRESULT: 0x80040155) on Nuget

I've been using Nuget up until today and suddenly been hit with the following error:

Interface not registered (Exception from HRESULT: 0x80040155)

No more details are provided. It happens if I open the "Manage Nuget Packages" window or I open the Nuget console. It happens on VS2010, 2012 and 2013. I've tried unstinalling and reinstalling all versions and no change. As I said it worked last week, I have updated VS 2012 to update 4 since then but don't see why that would affect other versions of VS.

Any suggestions?

Edit: I've found the following detail in the devenv /log ActivityLog:

at EnvDTE._DTE.get_Solution()
   
at NuGet.VisualStudio.SolutionManager.get_IsSolutionOpen()
   
at NuGetConsole.Host.PowerShell.Implementation.PowerShellHost.UpdateWorkingDirectory()
   
at NuGetConsole.Host.PowerShell.Implementation.PowerShellHost.Initialize(IConsole console)