With this error, the hard drive likely has failed. You can go to: http://www.hitachigst.com/hdd/support/download.htm#DFT and make a bootable floppy or CD and run the test. The test will advise the condition of the hard drive. If it has failed, it will need to be replaced, and the operating system and its files installed again.
It may also be that the operating system has been corrupted by virus or other means, requiring that the operating system and its files be installed again.
Hope this helps.
Chris
September 2006