Notice: I have now rebuilt my machine to remove this bug, so I can no longer verify any answers.
I recently installed Internet Explorer 9, and activated the development tools by pressing F12; I then clicked "script" and the "start debugging" button but I got the following error:
Unable to attach to the process. Another debugger might be attached to the process.
I get this message regardless of the site I am on (currently I'm on google.com). I have no other applications running, and have rebooted my machine.
Can anyone suggest why this may be appearing?