-Windows 8 only-
First, a little about Windows 8 Toobox:
With Toolbox, you can view and interact with up to 6 different tools at once, giving you the power and flexibility to customize your workspace for maximum productivity. Toolbox allows you to run more than one instance of any of these tools within the same workspace. This allows you to view multiple web pages at the same time, monitor the weather in two different cities, or even view the time in six different locations at once.
With the Toolset feature, you can save your favorite layouts and customizations to be recalled quickly and easily whenever you need them. You can even pin them to your Start Screen!
My problem: Toolbox wouldn’t load. So I went searching for some answers and this is what I found…
There are currently 10 apps included in Toolbox with promises from Microsoft of many more to come :
Download and run the Modern UI App troubleshooter to check your apps.
Other possible solutions via Microsoft Answers