Here's how I fixed my Zen Xtra with a similar problem, using the following instructions from Creative Support
According to your email, it seems that you are having difficulty with your Zen Xtra after attempting to upgrade its firmware, apologies for having such difficulties. We will try to resolve this by following step by step procedure to get your player up and running again.
Here are several steps that you may need to try to be able to resolve the issue.
Please do take note that it is necessary to perform this whole operation on PC running on Windows XP and with Windows media player 10.
1. Uninstall all creative software & drivers.
2. If you have Windows Media Player 11 installed, i will need you to uninstall Windows Media Player 11 and Media Player 11 runtime (will require a reboot for each thing). This is done by going to add/remove programs and uninstalling (this will put your pc back to wmp10).
3. Re-install the Zen Driver from the creative website and reboot. The driver can be downloaded via link: Creative ZEN and Jukebox Driver 2.01.00 (1.86 MB) - JB3MV2_PCWDRV_US_2_01_00.EXE
http://files2.europe.creative.com/manualdn/Drivers/PDE/9758/ENG/Bin/0x529B87A2/JB3MV2_PCWDRV_US_2_01_00.EXE
4. Plug Zen in.
5. Make sure you have the firmware update ready, run it but don't click the language bit yet), leave the mouse hovering over your language selection. The firmware can be downloaded via link: Creative Zen Xtra firmware - ZenXtraP4SAudible_PCFW_LB_2_10_03.exe
http://files2.europe.creative.com/manualdn/Drivers/PDE/9092/0x4F2D1A07/ZenXtraP4SAudible_PCFW_LB_2_10_03.exe
6. On the Zen - select "reload OS", from the recovery menu. You may refer to this link for more information on accessing the recovery mode under 'ZEN series of player':
http://uk.europe.creative.com/support/kb/article.asp?l=3&sid=4794
NOTE: If you are not able to access recovery mode, please install the firmware update directly.
7. As soon as it flashes up "reload new firmware now via USB" click the language button
8. Now the pc should find it and allow you to re-load the firmware. (it may take a few attempts)
9. Once complete, click close and restart the pc.
Mark Crowne, September 2007