I guess the installables for the BE are corrupt. I would request you to please go to the
www.backupexec.com and on the right hand side you will find the trialware. Please download the trialware for "Backup Exec 2010" and try installing with these new installables and see if that works. If not please check the logs directory in c:\Programsdata\symantec\backup exec for any logs generated there. Also please try to run the setup.exe from your installables in "WinNT\Install\BE"