Trying to open an ASPX page in design mode, these error appears.
It's an incompatibility issue between Windows and Visual Studio Languages.
The quickest and easiest solution is to open Visual Studio, if you show us the message that if we load the package in a language we say NO, then we will go to Tools-> Options-> Environment and International Settings.
There's language choice with 2 options, first is the language which Visual Studio is installed and the other is: Same as Microsoft Windows, so for openning the design view, we must select the option where we installed Visual Studio, then load the packages with the instruction devenv / resetskippkgs from the command line along the route: C: \ Program Files \ Microsoft Visual Studio 9.0 \ Common7 \ IDE, start Visual Studio and go!!.