Launch_msg: socket not connected! How can I restart my MB?

I'm on a white Macbook with Snow Leopard. It stops its boots 49 times to 50. The once it starts correctly (I don't know why!) the system is unstable (USB don't work and things like that).

Tried to boot with esternal HD, with OS DVD, with various cmd-alt-... modes: nothing!

It looks like there is an unrepairable error on disk (so, why 1/50 times it starts? Or why it doesn't starts with esternal HD anyway?). Even OS DVD utility disk can't repair my HD. Anyway, sometimes it starts, and I'm not sure the HD is the problem.

With cmd-V boot, I obtain these last LOG lines of error. Is there the problem? How could I fix it?