|brettrocdoc, What caused it was that when you closed the Task Manager you may have accidently double clicked near the "X" which will hide the tabs. Try it and you'll see the tabs disappear. You can then double click the upper right border and the tabs will reappear. It's nothing to worry about. The link below explains it under:|
Why does Task Manager look different? Where have the menus and tabs gone?
Task Manager has two different views. To see the view that includes menus and tabs, double-click the border of the Task Manager window. To switch back to the view without menus and tabs, double-click anywhere in the border around the tabs.