Here are some questions for you:
1. What size is the disk of your player?
2. How are you removing your player from your computer? Are you dismounting it from Windows or just taking the USB cable out?
3. What technique are you using to format your player? Are you formatting from Windows or the MP3 Player Tools?
Here is something quickly you can try:
- In your player, go to "System Setup" or "Setup".
Look for "Online Mode" and select it.
Make sure you set it as "Normal" instead.
Now try formating your player and see if that works.