It sounds like some of the system files may be corrupted. Please follow the procedures outlined below to let XP restore all system files.
1. Start the Operating System from the CD-ROM
2. When the computer starts from the CD, the system checks your hardware and then prompts you to select one of the following options:
* To set up Windows XP now, press ENTER.
* To repair a Windows XP installation using Recovery Console, press R.
* To quit Setup without installing Windows XP, press F3.
3. Press ENTER.
4. Press F8 to accept the Licensing Agreement.
5. A box lists your current Windows XP installation, and then the system prompts you to select one of the following options:
* To repair the selected Windows XP installation, press R.
* To continue installing a fresh copy of Windows XP without repairing, press ESC.
6. Press R to start the automatic repair process.
Note: After repairing Windows XP, you may need re-download all updates.