5th Gen Ipod Touch erasing all music after adding new files.

I have a 5th Gen iPod touch and this is about the 9th time this has happened. I was adding new music to my ipod. I got an error (ipod cannot sync too many files open) So I eject my ipod and restart my computer (Windows 8) and plug in the ipod. I had to erase some music to add 2 songs. after staring at the sync bar for 5 minutes, I look at my ipod and everything is gone again. It's been restored many times. no apps on it. I use it just for music. and had over 9,000 songs on it.