What this means is that something has gotten corrupted on your system, while it was trying to Install. It is now damaged. You need to go and clean out the Windows Temp folder, this should be where the files get extracted from the hosterdemosetup.exe file that you downloaded from our website. Once you do this, it should work.
Here is what Installshield states about this error:
http://consumer.installshield.com/kb.asp?id=Q110646
We don't have this Installation set as a Web Install. When you download the file from our website, are you saving it to your computer or just clicking Open or Run? If you are doing this, then this is your problem. You need to click Save, save it to your computer. Then once it is on your computer, run the program from your local system.