Windows 2003 Boot Error
Have anyone of you installed Windows XP on a machine which is having Windows 2003. If you have, you may have noted that after Windows XP installation Windows 2003 stops booting up. If you do try to start Windows 2003 in safe mode it will stop at CRCDisk.SYS.
The reason behind this is that when Windows XP installs it will replace some of the required common files with Windows XP version. When Windows 2003 tries to start it will fail since it cannot find the required files.

To start Windows 2003 again you have to replace 'NTDETECT.COM' and 'ntldr' on the boot drive (C:). These two files are located in the Windows 2003 CD inside I386 folder.

If this does not start Windows 2003 try running Windows 2003 setup again up until the first restart. When the system restarts Windows 2003 should start as normal.

In the worst case if that also wont solve your problem then you have to repair your Windows 2003 installation by continuing Windows 2003 setup and selecting Repair mode.