UPDATE: Quick fix - Select MAT's repair option from Programs and Features.

The root issue is that MAT adds required references in the "devenv.exe.config" file that are removed when the Update 2 RTM is installed.  These references are added when MAT is installed and removed when uninstalled. Applying Update 2 RTM overwrites the config file, which causes MAT to misbehave.  The fix is to simply run repair MAT from Programs and Features as this will read the needed references.  Of course, uninstalling and reinstall also works. 

Sorry for this inconvenience.

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Some users are reporting that after apply Visual Studio 2013 Update 2 RTM with MAT already installed is blocking solution file renames.  This appears to only affect machine that updated from Update 2 RC.  We are looking to the problem, but Joost van Schaik has blogged his solution that claims an uninstall and reinstall of MAT solves the issue.  Here is a copy of the blogs contents for quick reference. 

“A couple of people – me included – have been suffering from the fact that, after they applied Visual Studio 2013 update 2, it became impossible to rename files from Visual Studio. This highly annoying problem was occurring only on my Surface Pro, and not my Core i7 desktop. The difference was that the Surface Pro at one point ran the public RC of VS2013.2, and the desktop did not. Even totally deleting VS2013 and reinstalling it did not work

Today I got the golden tip from a fellow name Chung Bill (unfortunately I know only his name and e-mail address): apparently, if you did follow the upgrade path from public RC to RTM and you have the Multilingual Application Toolkit (MAT) installed, something goes wrong. The solution is also very simple: uninstall the MAT, then reinstall it again. If you then fire up Visual Studio 2013 again, renaming files works again. Note that you have to uninstall it from Windows, using Programs and Features, not from inside Visual Studio.

Somewhere in the intricate woven components of the MAT and VS2013.2 something apparently went wrong. But fixing it ain't rocket science. No harm done. Nothing broke permanently ;-).
The original blog is located here: Fix for being unable to rename files after applying Visual Studio 2013 update 2

We will continue to look into this issue to ensure that everyone is unblock as soon as possible.

Thank you,
The Multilingual App Toolkit team  
multilingual@microsoft.com