How did you purchase the McAfee programs, could you please provide us with your Customer ID for McAfee (or) Dell Service Tag
Did you previously have any security software installed?
What type of operating system? Windows 7 XP Vista
Did you ever have any virus or malware issues?
What browser are you using? IE8 Firefox Opera
Please answer the questions above for both computers 2 and 3
On computer 3 you might want to run the McAfee Preinstall tool before attempting to install the software. See this link http://service.mcafee.com/faqdocument.aspx?id=TS100119 after running the tool reboot and then proceed to install your software.
After several more attempts I was finally able to get McAfee on my other computer. Thank you for your help.