Cannot install iTunes 7 (re: InstallShield Isscript error message)

I keep getting the message that my ISScript.msi engine in InstallShield on my PC is too old and needs to be upgraded in order to successfully download iTunes 7. However, the error message continues to persist and foil the iTunes installation even after updating with the correct ISScript engine. I even replaced my InstallShield folder with the InstallShield folder from my laptop where I was able to download iTunes 7. This did not work either...Nothing seems to help....PLEASE HELP

Dell 8300 Windows XP Pro