demo not installing"""""' Help''''''

[MTUSUPPORT]

Here is what they say the fix is on Installshields website.

This error will appear if the InstallScript engine could not be installed on the machine. In this situation run ISScript.msi to uninstall the engine if it already exists or install it for the first time. This error could also result from insufficient DCOM permissions on the machine.
To set DCOM permissions:

Launch Dcomcnfg.exe from the Start, Run option.
Go to the Default Security tab, Default Launch Permissions section and click Edit Default.
Now set the privilege "Allow Access" for yourself from the drop down list.
Click ok and close Dcomcnfg.exe
Run the setup again.