When a user has a SolidWorks file that was created with 2011 and they open it with SolidWorks 2012, the system will ask the user if the file should be converted to 2012.  Does anyone know of a way to prevent this?

We have some users that will be working on 2011 and 2012 files and we don't want them to convert the 2011 files to 2012 by accident.

Thanks!

Tom