If you see an image of the table the way you'd expect it to look if you were playing it, then it's running.
Now, possibly it's lost focus for some reason and your system is displaying it in the background. That could be a reason the keys aren't working. That's a system issue.
If that's the case, you could mouse over the image and click on it to activate it. Nothing would immediately happen, but the table should regain focus. As an alternative, you could hit ALT-TAB a few times to cycle through your running programs, just so you could bring it back to the active table.
Try playing with those things, then hitting the keys mentioned earlier.
If that doesn't work, please let me know what your VP version is. You can check that by going back to the editor and choosing "Help" and "About" from the drop-down menus.