Internal error 3 during Client Installation Netbackup v 7.6.1

Errors in Installation - 

09-07-2015,13:15:04 : DEBUG: Error 2738: Could not access VBScript runtime for custom action
09-07-2015,13:15:04 : ERROR: Internal Error 2738.
09-07-2015,13:15:04 : Action ended 13:15:04:
setRegistryValues.B2D5B6C9_4698_42F7_AC9D_955789A69556. Return value 3.
09-07-2015,13:15:04 : Action ended 13:15:04: INSTALL. Return value 3.

Solution - 

GENERAL ERROR: During the installation of NetBackup, the installation fails with Internal Error 2738

https://support.symantec.com/en_US/article.TECH57368.html

SOLUTION/WORKAROUND: 
1. Open a Command Prompt(cmd) as the Administrator.

2. At the command prompt, run the following command:
x86 Windows OS:
cd C:\Windows\System32

x64 Windows OS: 
cd C:\Windows\SysWOW64

3. Then run the command below:
regsvr32 vbscript.dll

If an error was received attempting to register vbscript.dll, please restart the computer and attempt to register vbscript.dll once again.  It is possible that the administrator has settings that prevents vbscript from running.  Check with your administrator.

Check Security settings on your server. There is something preventing the installation from using vbscript.

You can also check your application log is any related event is logged.

Here is a procedure to forcefully remove the registration. PLESE TRY THIS ON YOUR OWN RISK - 

Please make sure you BACKUP THE REGISTRY/system before you make any changes to the registry.
To delete the registry keys, please run following commands in a command prompt with Administrator privileges. 

reg delete "HKCU\SOFTWARE\Classes\Wow6432Node\­CLSID\{B54F3741-5B07-11CF-A4B0-00AA004A5­5E8}" /f
reg delete "HKCU\SOFTWARE\Classes\CLSID\{B54F3­741-5B07-11CF-A4B0-00AA004A55E8}" /f

To Re-register the DLL please run following commands with elevated privileges.

c:\windows\syswow64\regsvr32 vbscript.dll