This time it was scary... and I'm still scarred because I'm not sure what happened and if it will happen again. I hope it's not a hard-drive problem but it sure looked like it even thou the Disk Utility didn't report any problem.
I had shut down the laptop for a while and when I came back, it didn't start. There was no rEFit menu as the MacBook seemed to go directly to Mac OS X. But Mac OS X wouldn't start either. I would get to this screen where a progress bar appears but the progress bar kept returning to zero and start all over again.
I then booted using an Ubuntu Live CD holding the "c" key at start up. It booted fine and all my data seemed ok. So I backed up all of it to another computer. Again, Linux saved my day.
I then tried to reinstall over the current partition but no go. The installation utility kept telling me some error occurred trying to install and advising me to try again. The only way I found to install OSX was by removing all existent partition and start all over again.
The MacBook and Mac OS X seem to be running fine at the moment but I am not very comfortable with all this...
I hope this is not any hardware problem but I miss Linux anyway and I'll probably be switching back to Linux as my main home operating system. I just feel a little tied up with Mac OS X and this kind of problems make me feel impotent because it's hard to tell what's going on under the hood. Why is the installation failing? Why oh why??