Shut down IE. Reopen it. Open a second window (presumably minimised). Close down original windows and then resize second window to full screen.
Close second window. On rebooting the problem should (but not always unfortunately) be solved.
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New iPad, iPhone SE & Red iPhone 7 on sale now
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.