How do i inlock my 80gb ipod without loosing the music

SOURCE: Apple 80gb iPod freezing/computer wont recognise iPod

Try it on another computer and if it happens its the ipod. Or try restalling itunes with the lates version (7.7.1)
If that doesnt work try using a different program for your ipod eg Jriver media center

SOURCE: Getting ipod to record music

Symptom When opening iTunes for Windows you may see the following error message:
"iTunes might be unable to launch or communicate with iPod or iPhone. For help repairing your operating system, click More Information." Products affected

• iTunes for Windows

Solution This symptom may be caused by an issue with the digital signing of Windows XP drivers. First, update to the latest version of iTunes. You can download the updater here or in iTunes, choose Help > Check for Updates.
If the issue continues with the latest version of iTunes, try following the steps below to reregister several .dll files, which may resolve this issue.

1. Quit iTunes.
2. Highlight all of the following 10 lines of text that begin with regsvr32 and then choose Copy from the Edit menu of your web browser: regsvr32 /s softpub.dll
   regsvr32 /s wintrust.dll
   regsvr32 /s dssenh.dll
   regsvr32 /s rsaenh.dll
   regsvr32 /s gpkcsp.dll
   regsvr32 /s sccbase.dll
   regsvr32 /s slbcsp.dll
   regsvr32 /s mssip32.dll
   regsvr32 /s cryptdlg.dll
   regsvr32 /s initpki.dll
   
   
3. Open the Notepad program by choosing
   Start > All Programs > Accessories > Notepad
4. In Notepad, choose Paste from the Edit menu. Note: make sure that the text that appears in Notepad is the same as what is shown above.
5. From the File menu, choose Save As.
6. In the File name field type appleitunes.bat and save the file to the Desktop.
7. Close Notepad and locate the appleitunes.bat file. It should appear on the Desktop with the icon shown below:
   
8. Double-click the file and you will see a black window appear on the screen for about a minute. Wait until the window automatically disappears and proceed to the next step.
9. The appleitunes.bat file can be deleted at this time.
10. Open iTunes.

Additional Information Because some malware may unregister the .dll files, make sure you have the most recent updates to your anti-virus software and then do a full scan of your files.

SOURCE: ipod saying no music but says there is 20gb left from 80gb

i never ever had such problem even if u remove widoud disablin (safe remove). try formating ur ipod then copy your stuff and if yet dont work then replace it if it is in warranty