I had not run Disk Warrior (Alsoft)  for some time and my computer was getting buggy. The computer would not shut down properly. I decided to run that utility and it came up with a whole lot of directory errors. After the utility repaired the directories I had another problem.  My .Mac synchronization would not work. When I went into the Control Panel and clicked on the .Mac icon I got a keychain error and the splash screen looped so I could not quit. I had to press Command + Option + Esc to force quit the Control Panel. I went into the Applications folder and into the Utilities folder to find the Keychain Access application. I found the .Mac account and tried to change the password but it would not allow me to do so. I went into the Keychain Access menu and chose Keychain First Aid. I asked that application to repair the keychains and it did find a lot of errors and repaired them. I tried again to change the .Mac password from within the Keychain application (Login + All + .Mac Password) but again I could not enter the password. From the Internet I discovered that all I had to do was delete the .Mac Password entry. The next time that password was needed I had a chance to enter the correct password. Sure enough, I went into the Control Panel and chose the .Mac icon and no more error message showed. The password was blank. I entered the correct password and it worked perfectly.