I just switched from a 32 to 64 bit system and trying to install Avast, the setup fails. Attached is the log file generated. Hopefully someone can interpret what it means…
Try to clean the TEMP folder (“C:\Documents and Settings<your profile>\Local Settings\Temp”) and run setup with commandline:
setupeng.exe /forceinstall
If it doesn’t help, you can try to install the latest beta version