Are you running Kaspersky security software on that PC? (There's been a few reports in recent times of Kaspersky interfering with iTunes installs, with that message being produced.)
If there is Kaspersky on board, we should try some general-principles getting-past-security-software-interference troubleshooting.
Download and save a fresh copy of the iTunesSetup.exe (32-bit installer file) or iTunes64Setup.exe to your Hard drive. (Don't run the install on line, and don't start the install just yet.)
Restart the PC. After the PC restarts do not open any applications. Disconnect from your network and/or the internet. Now switch off all your security software (firewall, antivirus, antispyware).
Now start the install by doubleclicking the iTunesSetup.exe (or iTunes64Setup.exe) file you downloaded earlier.
Reenable all security software prior to reconnecting to your network and/or the internet.
Any better luck with the security software shut down?