I've solved this problem on the IRC channel (thanks davidh2k !) and I just want to explain so it can be useful for others.
After upgrading from 0.5 to 1.0 with a clean install, I had permission problems on my shares so I couldn't write in some folders. The solution was to use ACL and set read/write/execute for the group on the shared folders (and apply that on the subfolders). Before it was only read/execute.
Bye!