Visual Studio object browser not showing AjaxControlToolkit dll

Visual Studio object browser not showing AjaxControlToolkit dll

Visual Studio 2010. I have just noticed that the Object Browser is not
showing some objects!
In my Bin folder I have, for example, the AjaxControlToolkit.dll and
FreeTextBox.dll
In the Object Browser 'Browse is set to 'All Components'
The Object Browser Settings are:
View Namespaces (ticked) View Containers (NOT Ticked) Show Base Types
(ticked) Show Derived Types (ticked) Show Hidden Types and Members
(ticked) Show Protected Members (ticked) Show Other Members (ticked) Show
Inherited Members (NOT ticked) Show Extension Members (ticked)
Any idea why the AjaxControlToolkit.dll is not showing? And others?
They definitely used to be there as I use Object Browser all the time to
inspect properties etc. expected by classes etc.