I have been unable to drag-n-drop to reorder slides as I used to. This just started not working out of the blue. Also noticing glitchy behavior when I using the undo arrow. It doesn't work to undo the last thing I did. The screen flashes as though the command was recognized, but the object that I sized and want to go back to the original remains resized - without me having saved the file in between. What's going on? Has this happened before?