you can visit the Phillips support site
www.philips.com/support
Enter your model number on the search box and download the Device/Firmware manager from the Software and driver section. You can now upgrade the firmware.
If you still have problem, I'd suggest that you repair your GoGear with Device manager. Here is how:
Launch Device Manager and click the Tool menu and select "Repair", then follow the instructions to perform the repair process. Make sure all other applications such as Philips Plug-in, Windows Media Player or Windows Explorer that access the device are closed or else Device Manager will not recognize the device.
Contents may be removed by using this function. So make sure to back up your contents.
Hope this helps.