In order to fix the issue, you need to to perform a clean reload of the BlackBerry Device Software. For this purpose, visit BlackBerry official web page and download and install BlackBerry Desktop Manager on your computer. After that, connect your device to your PC using the USB cable and launch the software. Go to the Device menu, select Update and click View other versions from the lower left corner. Check your Blackberrry OS box if it is not automatically detected and click Install. Un-check the Back up device data option and press the Install update button.