Dernières nouvelles concernant la version 10 de Stuffit expander et effectivement le problème peut venir de là. En anglais désolé j'ai la flemme de traduire mais à priori rien de compliqué à comprendre je pense
Shortly after release of StuffIt 10 a problem was discovered that affects some users. When the version checking code in the StuffIt applications polls the network interfaces on the Mac to see if any are active, it checks for an IPv4 or an IPv6 address. If IPv6 returns <null> because it is disabled, or for some reason never got an address, this version checking process crashes. This is problem occurs in all StuffIt 10 apps that use version checking when there is no IPv6 address.
The StuffIt applications that do version checking on launch are:
StuffIt Expander
DropStuff
StuffIt Deluxe application
StuffIt Express PE
The following work-around resolves the issue:
1 - Go to System Preferences->Network
2 - For each active interface, go to the "TCP/IP" page
3 - Click the "Configure IPv6..." button and set it to "Automatically"
4 - Click "OK"
5 - Click the "Apply Now" button
You should see an IPv6 address right above the "Configure IPv6..." button
6 - Save the preferences
7 - Try launching your StuffIt 10 apps again
Most OS X installations that we've encountered have both IPv4 and IPv6 addresses. If you must have IPv6 disabled, this workaround will allow you to launch the StuffIt applications listed above successfully and then disable the version checking in each. After doing that, you can then disable IPv6 again and use these StuffIt application without any problems.