Please unplug all external peripherals and restart the system.
If the issue persists, perform the steps mentioned below:
Check if the hard drive is detected in the BIOS.
Restart the system and press F2 or Delete to open BIOS menu. Ensure that the hard drive is detected in BIOS.
If the hard drive is detected, restart the system and press F12 for One time Boot Menu. Select diagnostics or Utility partition to perform hardware diagnostics.
If the hardware diagnostics pass with no error codes, perform Windows XP repair using the link mentioned below:
NOTE: Press F12 on Dell Logo for One Time Boot Menu. Select CD/DVD drive to boot the system using the optical drive(This will set Optical drive as the first boot device for a single boot).
Thanks & Regards