Hello,
we would suggest you totally uninstall 8.0 version along with the updates, and then make a fresh install of 9.x version that you are trying to install.
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You can also go through the following doukument:
Troubleshooting VERITAS Backup Exec 9.0 for Windows Servers installations
http://support.veritas.com/docs/252437
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Hope this helps you....
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