Windows XP Boot Files and Boot Errors
Just as MS-DOS and Windows 9x suffer from boot problems, so does Windows XP. This section takes a look at some of the boot problems that affect Windows XP computers. These problems will affect all Windows NT-based computers, such as Windows 2000, Windows Server 2003, and Windows Vista.
The Windows XP boot process may suffer from boot sector corruption, boot loader problems, and drive identification problems within boot.ini. For most problems, the Emergency Repair Process or Recovery Console are reasonable troubleshooting and repair steps.
The boot.ini file on your hard drive identifies the controller bus that contains the hard drives in your computer. This controller bus is identified as either SCSI or multi. If your drives are connected to a SCSI controller with the BIOS disabled, the controller is identified as SCSI. In all other circumstances, the controller is identified as multi. If your system is unable to initiate the boot process, or if you receive an error regarding a missing ntoskrnl.exe, then the problem could be a misidentified SCSI controller.
No operating system found
The "No operating system found" error in Windows XP, just like in MS-DOS, is tied to severe corruption of the boot sector on your hard drive. To restore your drive to working condition, you should perform the Emergency Repair Process to restore the boot sector on your hard drive. Minor corruption of the boot files would report missing files, such as ntldr or ntdetect.com, and the next section will tell you how to deal with missing files. As with MS-DOS, the "No operating system found" error could be caused by having left a formatted floppy disk with no boot loader in the floppy drive during boot.