You should not reinstall Mac OS X Server 10.1 (build 5K10) from CD-ROM over an existing Mac OS X 10.1.1 installation, which would be after the Mac OS X Update 10.1.1 or the Mac OS X Server 10.1.1 update (build 5N13) has been installed.
If you need to reinstall Mac OS X Server 10.1, you should back up data and erase the affected hard disk or partition prior to installation. Follow these steps:
1. Back up important data, customized configuration files, and documents stored on your Mac OS X Server 10.1 disk.
2. Erase your Mac OS X Server 10.1 disk. You may do this using the Mac OS X Server 10.1 Installer.
3. Install Mac OS X Server 10.1.
4. After installation is complete, install the Security Update 10-19-01, the Installer Update 1.0, the Mac OS X Update 10.1.1, and then the Mac OS X Server 10.1.1 update again.