This dialog is telling that there is a bad spot on the hard drive and you should correct the problem.
I assume you're running Windows XP...
If so, right click on the My computer Icon and choose "Explore"
In the Windows Explorer window, click the + sign next to my computer and expand the folder.
Then right click on the C drive and choose Properties.
Run the Disk Cleanup tool and allow it to remove excess junk files (like Temporary Internet Files/ Recycle Bin files, etc.)
Then click the Tool tab and click the Error Check button. Click the both option and OK your choices. You will see a dialog box open advising you that the request cannot be completed until you restart your computer. Say yes to the dialog. OK (close) the window and restart your computer.
These two scans will take several hour to complete, so you may want to do this overnight.
The check disk tool will attempt to repair a bad sector on the hard disk that is causing this error dialog telling you that a portion of your system cannot be accessed. It will "build a bridge" around the bad area.
If you desire to repair the bad sector rather than bridge around it, you can purchase a program called "Spin Rite" which:
By operating directly upon magnetic storage media at a level below any installed operating system, this major milestone release of SpinRite is able to operate on all Windows XP NTFS formats, all DOS FAT, all Linux file systems, Novell, Macintosh (if temporarily moved into a PC) or anything else — it can even be used to repair and recover the hard drive from an ailing TiVo!
I have used this product and I really like it, but you may be just as satisfied with the built in "check disk" tool native to Windows.
