Thanks for your help guys, it works smoothly again !

Only weird thing: after entering that 'sync' command, I didn't get a command prompt for, say, two hours...
I wasn't worried too quickly, because some commands before 'sync' also took about one hour to complete.

But after waiting that long I gave it a shot and found out I just had to hit enter to get back to the comand-prompt... I felt a little bit stupid...