Could you please do the following and then post back with your progress?
1. Remove the battery from the device then place it back in and allow the device to restart.
2. Ensure your computer has been restarted since Desktop Manager was installed. Also confirm that during the installation you selected "BlackBerry Internet Service".
3. Open BlackBerry Manager and connect your device. Then in Desktop Manager select "Options" and "Connection Settings" and set the connection to USB.
If you still continue to have issues you will have to perform a clean uninstall and then reinstall using the following steps:
http://www.blackberryforums.com.au/f...-software.html