If you experience any issues with Displayforce Player firstly you should try updating it to the latest possible version. To do it you should press the "Update" button in the Player's main screen.
If an update didn't fix the issue - try rebooting the device.
If none of these ways helped you fixing the issue - please contact us. To help us fix the issue - please describe what issue are you experiencing, what is the version of the Displayforce Player and if possible provide us a remote access to your device.