iPod shuffle 'enable disk use' is not available

If you use the Autofill feature, you have the Manually manage music setting enabled on the shuffle's Summary screen. When you have Manually manage music enabled, it is required that the Enable disk use setting is also turned on. This is because when you manually load the shuffle (or use Autofill), instead of using automatic syncing, iTunes needs to keep the shuffle's "disk" mounted by the system continuously. That is why the you cannot uncheck the Enable disk use setting. If you turn off Manually manage music, and use automatic syncing, you would be able to uncheck the Enable disk use setting

I think you may have copied some files to the shuffle manually (outside of iTunes), that is about 400 MB in total size.

Windows Explorer and can see the music I already have put in it

You should NOT be able to see songs files on the iPod's disk using Windows Explorer. Those are probably song files you copied to the shuffle manually, outside of iTunes (the "Others 400 MB"). The "Audio 900 MB" portion is what Autofill put on the shuffle. Those files (any song files iTunes puts on the shuffle) are hidden, so you will NOT be able to see them using Windows Explorer.

So, the first thing to do is use Windows Explorer to delete all of those song files you can actually see on the iPod's disk. They should not be there. When you go back to iTunes, that "Others 400 MB" should be close to zero.

(OR, if you just want to start over, you can use the Restore button on the shuffle's Summary screen. This will erase the shuffle, re-install its software, and set it to default settings.)

This is how to load the shuffle manually, in case you did something different before to get those song files that were visible in Windows Explorer. First, show the iTunes sidebar, if it is not visible. From the menu bar, under View, select Show Sidebar.

Select Music under LIBRARY in the sidebar. Your songs are listed to the right. Find (but do not click on) your shuffle in the sidebar, under DEVICES. Drag songs you want on the shuffle from the Music library list and drop them on the shuffle in the sidebar. Do not drop songs on the shuffle outside of the iTunes window. (Alternately, you can select the songs you want on the shuffle in the Music library list, right-click on the selection, and select Add to Playlist -> your shuffle's name.)

If you loaded all the songs strictly using iTunes, then Windows Explorer should NOT see those song files. Song files loaded using iTunes are hidden, when you look at the disk using Windows Explorer. So if you see nothing, that is normal.

I can't read that message in the image. Is it saying something about the current (manually loaded) contents of the iPod being replaced when you use automatic syncing? You don't have to do that (uncheck Manually manage music)... I was just explaining WHY Enable disk use cannot be turned OFF (unchecked), IF you use the Manually manage music setting. That is normal too.

Did you previously load files manually on the iPod's disk using WIndows Explorerer? If you did, and dragged them to the Trash to delete them later, they may still be taking up space on the disk until you empty the Trash. That's how it works on a Mac. The files are still there (hidden), until the Trash is emptied.

Otherwise, I don't know what is using that 400 MB of space that counts as "Other." On a shuffle, it is usually files loaded manually outside of iTunes when Enable disk use is ON. The easy way to get rid of it is to do a Restore on the shuffle in iTunes. The button for Restore is on the shuffle's Summary screen. This will erase the shuffle (getting rid whatever is "Other"), re-install its software, and set it to default settings.

When you set it up again, you may want to use automatic syncing, instead of the manual methods. If you want more info on using automatic syncing effectively, please post back.

I think the 400MB is something else, not from using Autofill. It may even be some data corruption on the iPod's storage, that is causing iTunes to report 400MB as being used for something. In any case, doing a Restore should resolve the problem, because the disk is erased to give your shuffle a "fresh start."