I had similar errormessages a few months ago. Two days later my harddrive crashed and became unusable. My advice: MAKE backups of all your important files. Download a diskchecking program from the manufacturer of your harddrive and run it. In my case I had to use PowerMax by Maxtor, which told me that my harddrive was almost dead and it was a good idea to immediately make backups of my files! Which was already to late cause the only program that could access my drive was PowerMax.