Did you try doing a Restore on the iPod? If the iPod's hard drive has data corruption, that may be why it errors out at a certain point in the data transfer.
The Restore button is on the iPod's Summary screen in iTunes. This will erase the iPod's hard drive, reinstall its software, and set it to default settings. If the data corruption is not due to a hardware fault, the Restore should fix the problem.
NOTE: If there is a hardware fault on the iPod's hard drive, the Restore process may fail.
It is likely that the iPod's hard drive is faulty, and there is a problem with the iPod's storage media at about the point where 500 to 600 songs would be loaded. That is why it errors out consistently at about the same point in the data transfer, no matter how you load the songs.
You said you tried converting your song files from MP3 to AAC, so that would rule out a problem with the files being transferred.
It may be a problem with the connection between iPod and computer, but then, I think the problem would occur at a random point, not consistently when you get to about 500 to 600 songs.
You can set the iPod to Disk Mode
With iTunes NOT running, connect the iPod. If you have any Windows utilities that can examine a hard drive, you can try them on the iPod's hard drive.
You may want to try reformatting the iPod's hard drive using Windows (instead of doing a Restore in iTunes). The format type used on the iPod's hard drive is FAT32 (when the iPod is used with a Windows PC). If there is an option to do a "quick format," do NOT select that option. Do a "full" format (it may fail at that same point).
If that completes successfully, try running iTunes. It will probably prompt you to do a Restore, which you will need to do because the iPod does not have any of its software loaded. Then, see if your problem still recurs.
Currently Being ModeratedAug 5, 2013 10:06 AM (in response to Kenichi Watanabe)
I put it in disc mode and reformatted it though windows like you said and it said it failed when it finished so I restarted it and it loaded fine and it connected to itunes and then I restored it through itunes and then it did that fine. From their I tried to reformat it again through windows which it failed again. So I restarted it and the apple came up then after the apple came up it just shows a red x in a circle and below that circled x it tells me to go to The support website and nothing on website helped so I don't know what to do now.
Unfortunately, based on the information provided, my guess is that the hard drive in the iPod has become faulty. There is probably a portion of the hard drive storage media that has "bad sectors" and attempts to write data there causes failure.
If you have an Apple Store nearby, you can take it there to have an Apple tech support person at the Genius Bar examine it in person. You can make a reservation through the store's web page