Hi,
I have the last version that you mentioned on your message.
Sorry i uninstall the last version and let run microsoft security essential.
The warning message was in French " Windows installer a cessé de fonctionner "
This was the same warning message that i have few month ago with a release that was in conflict with " Windows installer "
The Avast Team found the problem and was able to reproduce it and they correct them.
I have only this on Seven pro 64, not on 8.1 64
I can understand that 7 is not supported by Microsoft any longer, but this is not this what there's such issue once again

Thanks, have a good we too

Gerald