Visual Studio 2010 IntelliSense doesn't select a default value - it just marks it

Question

I have a pretty annoying problem with the IntelliSense in Visual Studio 2010:

Every now and then (but not always - just out of my control) the Intellisense engine ch

Answer 1

For completeness, this option has a toggle button up on the toolbar:

Its visual status will tell you which completion mode is currently selected.