I have done something quite stupid. My original configuration was Mac OS 10.&.x, FileVault being turned on. As I thought that Mac os 10.7 Developper 2 was already safe (I always sued developper previews on iPhone without issues), I upgraded to 10.7. For a time, it was good. But too many bugs appeared and incompatibilities with installed softwar (I am the only one to blame). I though going back to 10.6 with a fresh, clean install, since I thought that those issues...