If you are a former Norton 360 user you may have an issue with ESET Smart Security V5 install seeing Norton and throwing an Error 1. Norton 360 had already been uninstalled on my machine and ESET V4 had been running for quite sometime. Uninstalled ESS V4 to install V5 and got a message from ESET V5 that Norton was installed. Used the ESET knowledge base Norton uninstall tool as well as the Symantec site Norton uninstall tool and neither fixed the the issue with ESET V5 seeing Norton. Tried several times. I used JV16 registry tool to search for all Norton and Symantec registry keys to delete them. Rebooted. After that, ESS V5 installed with no problem.