Well, you can’t sync. If you sync to the second computer, WMP will erase your first batch of music and put on the music from the second computer.
But you can just drag-and-drop the music from the second computer onto the Fuze.
But then beware. When you try to sync from the first computer it will erase the second batch.
The trick is to de-automate the whole thing.
Unless your music is from a subscription service (Napster, Rhapsody), or you must have WMP playlists, you don’t need WMP at all.
I’d start over.
First, look under Settings/System Settings to make sure you have a USB Mode switch. It’s probably in Auto Detect. Leave it for the moment.
Find where WMP is storing your music on your computers. Format the Fuze from Settings…which will ERASE ALL THE MUSIC ON IT.
Then switch to MSC mode under USB Mode. MSC is purely manual. From your WMP library, drag or copy the music onto the Fuze. Do that with the second computer too. Your music is on the Fuze and WMP doesn’t mess with it.
Then under Settings/System Settings