Sure thing, Picchu. I've found that Disk Warrior is a great utility for repairing file structures. You can also try "Repair Disk" in Disk Utility, and see if that works. Would you please copy & paste the results here?
Yes Disk Warrior can repair file structures, but I would not work on a system without a backup when the file structure is questionable in the first place. The first step is Data Rescue, Filesalvage, or Boomerang to attempt to rescue as much information as possible. Telling the difference between a file structure issue which Disk Warrior can repair, and can't is nearly impossible, and if your drive is nearing its end of life, you want to get information off it as soon as possible.
I left mine looping for maybe 45 minutes and it came up...no problems since. The install went without a problem, but it kept hanging at the white apple screen, rebooting after 5 minutes or so, and doing it over and over.
I am seeing something similar. My boot times have gone through the roof. It now takes about 5 minutes for the OS to load. Grey screen for a couple, apple logo for a couple then finally load. I was on with the support folks for a while, and we cleaned the cache, but eventually this came back. This is on a mini doing the standard update. I should have learned long ago to do the combo....
Basically, starting up the computer and holding down the "Shift" key. This will force a file system check of the operating system, and will in most cases fix any kind of file corruption that might be causing the stall. This will also clear out some caches. And the startup will take a bit longer than usual.
After this is done, just restart the computer again after it is successful.