Is this Windows 7 SP1? Also did you have any other security software installed previously, if so is it gone and did you run their removal tool?
Did the installer indicate any particular reason why it failed?
There is free telephone or online chat support available by clicking the Technical Support link under 'Useful Links' at the top of this page if you need it.
Refunds are available through Customer Service linked in the same area but hopefully we'll be able to avoid that.
Try the following steps before Installing McAfee.
Step 1 : Run McAfee Removal Tool and Restart the computer
Download the removal tool from http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe.
Step 2 : Run McAfee PreInstall tool
Download the PreInstall tool from http://download.mcafee.com/products/licensed/cust_support_patches/McPreInstall.e xe
Step 3 : Try Installing McAfee
For any Assistance you may get in touch with our online Tech supports. Links to Technical Support are provided under usefull links on top of this page.