Check this out....
http://support.veritas.com/docs/247448After a failed installation of NetBackup DataCenter or Enterprise Server, the re-install attempt prompts the user with a "Modify, Repair, or Remove" Options menu. All attempts to modify, repair, or remove the installation fail.
Exact Error Message
"Error 1723. There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor."
Details:The Microsoft Installer (MSI) installation process may be corrupted.
1. Download and install the MSI CleanUp Utility from Microsoft:
http://support.microsoft.com Description of the Windows Installer CleanUp Utility ( Q290301 )
2. Then install VERITAS NetBackup DataCenter (tm) or VERITAS NetBackup Enterprise Server (tm)