Yesterday we redeployed Silverlight Studio due to an issue with the SyntaxEditor Language Designer application that was discovered. Namely a licensing exception was occurring in a couple places where our .NET Languages Add-on was used. No other code changes were made to the actual Silverlight Studio products so the build number was not changed.
If you use the Language Designer and experienced this issue, please redownload the latest Silverlight Studio build to get the fix that will allow you to properly use all the features of the Language Designer application.