Thanks Peter, ...I think I may have found the culprit, ...I was just setting up a brand new HP EliteBook 8570p this morning and at the end of the setup it prompted me to install MS Security Essentials. I let it install thinking I would uninstall it later but forgot to and tried the NOD32 install and wouldn't install and presented me with the same error. As soon as I uninstalled Security Essentials the ESET install completed successfully. I plan to check the two previous machines to see if they have Essentials or some other AV or antimalware product installed and uninstall any I find. Thanks for the KB and uninstaller links, I'll use those if I keep spinning my wheels on this.