The problem is resolved for me. It wasn't a bug from Inkscape but OSX. A dirty installation of Maverick (without removing the old os) is the origin of the problem. So, because I'm a newbie on MAC, I made a complete reinstallation of Maverick (by removing Moutain Lion and formating) and Inkscape work...

My friend gets the same problem so I checked the logs (system.log) and the error message talks about SafeThread which isn't supplied. Inkscape[1554]: Performance: Please update this scripting addition to supply a value for ThreadSafe for each event handler: "/Library/ScriptingAdditions/ct_scrip...