Dave,
If you can drag the corners of the 'letterbox' to the corners of your monitor screen so that you see it as you would wish to, don't use the 'restore Down/Up button next to the red button, then, instead of using the cross in the red box to close the window, just for the first time go to File -> click Exit.
Close your browser.
Re open your browser and click on a link. If that is successful, then you can use the red button in future to close the window.
Not saying that will work but try it as it has worked for others that I have advised.
I don't know what caused the problem but hopefully it will be cured.
dave
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