I've done a lot of Googling for explanation and a fix, it took quite a while, so I thought I'd share.
The crash always happened when syncing photos. So after not getting very far with the usual suggestions I ignored all causes and fixes not relating to photos. The problem seems to have come from me replacing my iPhoto library with a different one since my last iPod sync. The solution (for me) was to delete the iPod photo cache folder.
- Find your current iPhoto library in the Photos folder
- Right (ctrl) click and select 'show package contents'
- In the new window delete the folder iPod Photo Cache
This link helped more than any other.