I am just gonna copy the entire entry for this error from eventid.net:
Error: "Class not registered" Server: D99E6E73-FC88-11D0-B498-00A0C90312F3. When backing up the system state on a remote system, Backup Exec uses Microsoft''s Certificate Services APIs to determine if Certificate Services is installed on the remote computer. If the check succeeds, Backup Exec enables the special routines to back up Certificate Services. If it fails, Backup Exec will not attempt to back up Certificate Services components. In addition, the Certificate Services APIs log an error to the Windows 2000 System event log on the backup server.
This error is a normal result of the API call determining that Certificate Services is not installed. The error can be ignored. If the error cannot be ignored, or if it is desired that the error not be generated, there is a workaround that will prevent the event from being logged: install Certificate Services on the remote servers that are generating the error.
Follow the steps bellow to install Certificate Services:
1. On the remote computer, go to Start > Settings > Control Panel and double-click Add/Remove Programs.
2. Select Add/Remove Windows Components from the left side of the Add and Remove Programs pop-up screen.
3. From the Windows Components Wizard, select Certificate Services.
4. Respond Yes to continue with the install of the Microsoft Certificate Services. After responding Yes to continue, the Certificate Services will be marked for installation.
5. Select Next on the Windows Components Wizard to finish the installation of Certificate Services.
Note: This error is generated as a result of a call to a Microsoft function. As a result, this issue can not be fixed in Backup Exec.
