Missing music files when loading iPod Classic.

I just finished converting all our albums and 45's to MP3 files. These all list and play fine in iTunes, but when I load the files on our iPod Classic, there are always about 50 songs missing. I have done this 4 times, and it's not always the same files, but always about the same number of files. The missing songs are about half missing at the beginning of the list, and half missing at the end of the list. I have 7455 files in iTunes, but after loading the iPod, there are around 7400 files actually on the iPod.

There is plenty of free space left on the iPod, The missing files are never the same songs as I try different times. The files are not corrupted, as they list and play okay in iTunes.

Any suggestions would be greatly appreciated. Thanks in advance for any help you might give.