On windows XP ... First make sure you know the drive where you installed your windows XP (for example c:) : I name it "Yourdrive".
If you have 2 operating systems installed, you can work from in the O.S. system that works well, if not try to work in save mode by pressing the f8 key at start-up.
When you're logged in:
Go to run ... type cmd ... enter ... type chkdsk "Yourdrive": /f /r
Press the "enter" key
When you have 2 operating systems installed, wait till all is finished.
Whith one operating system installed, your computer will have to restart because it can not make the changes whithout having a restart.
Hope this will help you all.
For those who cannot go in safe mode
To enter Recovery Console in Windows XP, you will need to boot from the Windows XP CD.
1. Watch for a Press any key to boot from CD... message similar to the one shown above.
2. Press a key to force the computer to boot from the Windows CD. If you do not press a key, your PC will continue to boot to the Windows XP installation that's currently installed on your hard drive. If this happens, simply reboot and try to boot to the Windows XP CD again.
How to Enter Windows XP Recovery Console
The Recovery Console can be an indispensable diagnostic tool when your Windows XP, 2000, or Server 2003 based computer suffers from certain major problems.
A number of commands are available within Recovery Console, some of them exclusive to the tool. When used, these commands can do things as simple as copying a file from one place to another or as complicated as repairing the master boot record after a major virus attack.
The chkdsk command, often referred to as "check disk", is used to identify, and often times correct, certain hard drive errors.