Cannot install AVG Antivirus Free

Hello James,
We regret for the inconvenience caused. Please check whether you have installed any other conflicting applications like McAfee, Avast, Norton etc… on your PC, If so please uninstall the conflicting applications. If the issue persists please let us know so that we could provide you with alternative resolution to fix the issue.
Thank you.

Running Vista - 64-bit.  Just uninstalled Kaspersky AV and want to put AVG Free back on my system until I can replace all Kaspersky installations in the house with AVG/multiple-computer.  I have downloaded the 64-bit version of the installer (AGV_Antivirus_Free_x64_693.exe), but it gets to a certain point and gives this error message:

! Installation failed  Sorry, we've experienced a problem… (etc.)
Error code: 0xC0070643
Description: Even exec_finished

I searched posts here and found one from last November, urging the user to run AVG_Remover.exe.  I did that and have tried a couple of times to install again, but same thing happens.  Can someone help, please?

James,
It seems that you have tried with all basic steps and since the issue persists we have sent you an email containing the instructions to have a better assistance in fixing the issue. Please feel free to contact us for further assistance.
Thank you.

Hello James,
We regret for the inconvenience caused. Please check whether you have installed any other conflicting applications like McAfee, Avast, Norton etc… on your PC, If so please uninstall the conflicting applications. If the issue persists please let us know so that we could provide you with alternative resolution to fix the issue.
Thank you.