It had Windows 7 installed with the configured Portuguese keyboard selection I chose upon first install.
However, sometimes in Visual Studio 2008 and 2010, the intellisense transformed my keyboard strokes in unknown symbols.
The problem? That pesky language bar intercepted Ctrl+Space key combination (used by intellisense) and applied the Chinese keyboard configuration that was factory-configured in my new PC.
After removing that Chinese stuff from my language bar (http://www.geekstogo.com/forum/Remove-Language-Bar-t2783.html) and my keyboard and Visual Studio started to work together immediately!