Does using crtl+l (the letter el) allow you to again select elements?
This causes the screen to redraw.
What view are you working in, the Edit Window, the DocMap, or other?
Do you receive any error messages?
If you right-click, then can you select "Select element"?
Can you select the element by hitting ctrl+e twice in succession? (This will continue up the ancsetory tree)
Can you triple click on some content of the element and get it to select the element?
(Double clicking selects the content. Double clicking on the element tag selects the element)