Developer tools not working in IE8

Check that there is no icon in the task bar for 'Developer Tool'.

There is a known issue that if you minimize or maximize the Devloper Tool window and then close the browser, the next time you start the Developer Tool it will open with the saved Window State (ie. The window won't be visible, but there will be a icon in the task bar).

To fix this right click on the Developer Tool icon in the Tasks bar and select Maximize from the context menu to maximize the Developer Tool window and then resize to your preferences. Close the browser to save the window size preferences of the Developer Tool and browser.

The next time you start IE8 the Developer Tool should open with the saved size and position preferences.