can no longer check the "enable forward and backward jump during playback" button.

Been using nero video (Version 16.0.4000) on win 7 pro machine for a couple of weeks burning mp4 and avi to dvd \ suddenly i can no longer check the "enable forward and backward jump during playback" button. I even reloaded files that i know for sure i was able to check the button on previously. but no luck... even tried to uninstall and reinstall with no love....its not greyed out... i dont even get a description of the button when i hover the mouse over it as before/with all other buttons? anyone have an idea how to rectify? this seems an essential feature not to have on a long movie. thanks in advance.