My Ipod Classic 160gb won't sync movies or T.V. shows properly without corrupting my whole Ipod.

I've had my Ipod for about 2 years now, and recently my Ipod has been unable to sync videos onto it properly without corrupting my whole Ipod. When i do sync a film onto my Ipod it will take file space but in the movies section it says "No Movies", however, when i do try to sync a movie it also corrupts my other files so my Ipod will say "No Music" as well. So i'll have to format and restore my whole Ipod and upload all my music on it again as well. Please can someone help me figure out how to sync movies and T.V. shows again without corrupting my whole Ipod.