Thank you !
I used Applejack on a previous install. I liked this software very much.
But on the broken install, I did not have Applejack (I forgot its name meanwhile ).
I hooked my SSD to another computer, and managed to install Applejack thanks to the Terminal (Applejack installer only accepts to work on the startup disk).
I booted in single-user mode, typed "Applejack", and saw that my Applejack install was a success : I could use Applejack to " repair disks". :-)
But when I then tried " repair permissions", I had the following result :
- All supporting services are not loaded.
Let's mount the startup file system for write access...
/dev/disk0s2 on / (hfs, local, journaled)
Configuring minimal Snow Leopard services...
And it's stuck there. :-(
I guess, Applejack tries to do the same as I did manually ("launchctl load /System/Library/LaunchDaemons/com.apple.kextd.plist"), and has the same problems.
So I guess, it's a good time for a reinstall. :-(
Anyway, thank you for your help !