Issues with installshield wizard

Hello, i am currently in the prossess of trying to install an mmorpg on my computer. the file fully downloaded, but when i try to install it it says:
"the contents of this file cannot be unpacked. the executable you are attempting to run has been corrupted. please obtain another copy of the file, verify its integrity and try agian."
I was wondering if anyone knew why this was or had any advice on how to fix it, because my computer seems to do this to about everything.
p.s. if it matters it was last chaos installshield wizard

 

Try turning your firewall and antivirus off, just while you run the download.

 

How?
(I'm seriously not that skilled with computers)

 

Both should have an icon in the System Tray (hover the mouse pointer over the icons). You may need to right-click on the icon or double-click it. Usually(?), you find an option to disable the program.

You may need to go to Start -> Programs, open the program and disable it from there.

Matt