Music disappears from iPod Classic after disconnecting from computer

I've got a somewhat puzzling problem here (or at least, I find it puzzling).
I'm going to go into great detail in the hope that it helps someone to point me in the right direction, and also in the hope that a potential solution might help someone else in the future – so please forgive me if some of the info here might not turn out to be relevant to the problem!

TL;DR: When disconnecting the iPod from my Mac (after ejecting from iTunes) the iPod thinks there is no music on it.
If you get bored by the details, please scroll down to the bottom for a summary of what I've done to try and fix this.

Background

I have an iPod Classic which I bought just under a year ago.

I use the iPod almost exclusively connected to the aux input of a car stereo (aboard a boat, actually), rather than with headphones.
I normally charge it via the USB mode of the same car stereo.

Every now and then, the iPod freezes. In particular, it very often freezes when plugging it into the stereo (USB mode) to charge, or when unplugging it. I simply reboot it (or reset, as Apple like to say) by holding down the play and menu buttons, and then all is well.

Recently (in the last couple of weeks) the iPod started to reset certain settings whenever it froze and had to be rebooted. After every reboot it would ask for the language to be set – something it never used to do – and it also sometimes reset other settings; such as enabling the clicking sound when scrolling.

The Problem

Yesterday, I plugged the iPod into my MacBook Pro (Late 2008, OS X Lion 10.7.2, iTunes 10.5.3), to transfer (I manage the iPod manually rather than with auto sync) some new music from my iTunes library.

When I finished, I ejected the iPod from within iTunes, as usual, and then unplugged the iPod when it told me it was ok to do so.
Rather than going straight to the music screen, as usual, the iPod rebooted (reset) itself. As I mentioned above, the iPod is sometimes a little strange about rebooting so I didn't think anything was strange. But…

When the iPod came on again, it had no music on it! Nothing. It appeared to be empty. Looking in the Settings->About screen, I could see that in fact the amount of space corresponding to my files was still being used – the hard drive hadn't been wiped, but rather the data, or the iPod's database, had presumably become corrupted in some way.

Fortunately I have all of my music on my Mac in my iTunes libraray, so this wasn't a total disaster. I thought I'd simply have to restore the iPod to factory settings and then put all my music back on. How naïve of me. I should know better.

When I plugged the iPod back into the computer, it didn't appear in iTunes. After some time, it appeared in the Finder, and iTunes froze. Ejecting the iPod took ages, and looking at it with Disk Utility caused Disk Utility to freeze. Odd.
I also tried opening exPod, just to see if it would work – but no; it also froze.
No combination of rebooting the iPod and computer, relaunching iTunes, etc, would make the iPod show up in iTunes.

Trying To Fix It

The first thing I tried was the iPod's built-in diagnostics, started by pressing menu+left whilst booting. But it couldn't find anything wrong.
I also tried starting the iPod in disk mode – it didn't help.

After everything else I could think of – including everything in Apple's awful support site, and failing to find anything relevant via Google – I eventually resorted to this technique (reformatting the iPod with Disk Utility), supposedly "The Super Fix for Most iPod Problems".
Actually I wasn't able to reformat the disk from Disk Utility, due to POSIX permissions errors, but I did eventually manage to format it from the Terminal using diskutil. And before you ask, I used the Extended Journaled format, with Apple Partition Map – as the iPod was previously.

And this fixed the not showing up in iTunes problem – I was able to restore the iPod from iTunes, and then add some music to it.

But guess what? Right. When I ejected it, it did exactly the same thing as before: the music all "disappeared", and the iPod wouldn't show up in iTunes.

More Attempts At Fixing It

Well, as you can guess, I was getting pretty fed up by now… But what could I do but keep on trying?

My next step was to format the hard drive as FAT32, from Disk Utility, and then initialise the iPod from iTunes as if it were a new iPod. This resulted in iTunes identifying the iPod as a Windows iPod, though in fact I had never connected it to Windows.

Now I tried adding content again, and this time, it actually worked! When I disconnected my iPod after adding one album to it, the album stayed on it!
Phew. Problem solved, I thought. Me being naïve again…

So, I proceeded to copy a few tens of gigabytes of music to the iPod, then I disconnected it – and we were back with the same old problem. F*ck. :'(

So, my final brainwave (well, maybe not…) was to actually format the iPod from Windows, via Parallels.
Unfortunately, I was unable to make iTunes on Windows download and install the firmware, but I did the next best thing. Just like above, I formatted the iPod as FAT32 from Disk Utility and then initialised the iPod from iTunes on OS X, resulting in an apparently "Windows-format" iPod, and then instead of adding music from my Mac, I connected it to Windows and added music from there.

So far (touch wood) I haven't had the problem when disconnecting from Windows.
So, I'm assuming this is a problem on my Mac (ie, in OS X) rather than on my iPod. UPDATE: I have now had the same problem on Windows, so I guess this is an iPod problem.

Summary

So, to summarise the problem and the step sI've taken to solve it:

• When disconnecting the iPod from my Mac (after ejecting from iTunes) the iPod thinks there is no music on it.
• When connecting the iPod to the computer again after this, it doesn't usually show up in iTunes. Occasionally it does show up, and iTunes says it is corrupted and needs to be reset.
• Formatting the iPod from Disk Utility and then restoring, or simply initialising, the iPod from iTunes doesn't solve the problem – it makes the iPod show up in iTunes again, but the problem occurs again as soon as I disconnect the iPod again.
• It doesn't make any difference if I format the iPod as HFS+ Extended Journaled or as FAT32.
• Managing the iPod from Windows, however, seems (tentatively; ie thus far) not to cause the problem.
  UPDATE: I have now reproduced the same problem via Windows.

So, what is the problem?

So, based on all the above, it looks like probably a problem in OS X. But I haven't been able to find out where the problem would be, or even for sure if it is an OS X problem.

I'd tentatively guess that it might be a problem with /System/Library/Extensions/iPodDriver.kext, but I don't know how I can check that (removing iPodDriver.kext stops the iPod from showing up in iTunes at all, and I don't know where I can get a "clean" iPodDriver.kext to replace it with).

UPDATE: I have now had the same problem on Windows, so I guess this is an iPod problem.

If anyone has any ideas, or can point me in the right direction, I'd be really grateful. I've reached the end of my troubleshooting abilities, and am at a lost end as to what else I can try.

Oh, and thanks for getting to the end of my monumentally long post! 😀

System Info

Mac:

• MacBook Pro, Late 2008
• OS X Lion 10.7.2
• iTunes 10.5.3 (yes, I know there is a newer version. I'm trying to download it, but havent had good enough internet yet)

iPod:

• Firmware 2.0.4 (latest version)
• Model MC293