Commented Unassigned: Input string was not in a correct format [3609]

I have upgrade to the latest NuGet version 2.7, and I now get the following error when trying to install a package. I am running on VS2012 Ultimate. I had all of the latest updateds installed. I did just install an update to VS for I believe the Windows Phone 8 that was in the extensions list. I also just installed the latest version of Typescript.

PM> install-package log4net
Installing 'log4net 2.0.0'.
Successfully installed 'log4net 2.0.0'.
Adding 'log4net 2.0.0' to Tyson.OperatorUpload.
Install failed. Rolling back...
install-package : Input string was not in a correct format.
At line:1 char:1
+ install-package log4net
+ ~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Install-Package], FormatException
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand

PM>
Comments: @choler: Which line of code throws that error message? It's a VS error message, so it's unlikely thrown by the String.Format() call. I want you to put a break point at the String.Format() at line 148. It will be hit multiple times. Every time it gets hit, press F10 to step over it. Keep trying that until you get the exception. When it happens, check the value of the 'message' and 'args' variables and share them here. If you are not comfortable with that, do you want to chat over Skype so that I can assist you step by step? Also, do you have any VS extension and/or add-in installed, besides NuGet? Could you try disabling all of them and see if it help.