Currently Being ModeratedJan 28, 2013 10:48 AM (in response to spirou781)
I had the same problem. In the end it turned out that I had moved the location of my Favourites folder to a different location -- iCloud sync does not like that but does not give any qualified error message.
Now that I have moved the folder back to its default location, all is working fine.
This is clearly a design fault on Apples side.
Hope this helps,