Gah! This is really causing me hassle today. Suddenly without warning \'@\' (at symbol) and \'\"\' (double quote) are trading places on my keyboard but ONLY in Visual Studio
U62- Perhaps people don't mark your solution as an answer if it's not an answer for them?
It's not a CTRL+SHIFT or any other key binding problem for me.
I do not even have US-International keyboard installed, yet Visual Studio constantly reverts back to it (I can see it in the Language bar, but when I go into Control Panel, it is not in the list of installed keyboards).
It's definitely something wrong with Visual Studio, because if I then move to Notepad, Notepad knows that the keyboard is UK. Move back to VS2010 again and it is back on US International.
EDIT: the answer is to go into Visual Studio settings, and select the International Settings pane. Make sure the Language is set to "Same as Microsoft Windows". "English" seems to be the US International keyboard English.