I recently replaced my 2006 PC with a new model that runs the 64 bit version of Windows 7. When I tried to install Zone Alarm the installation locked up my PC and then it kept locking up when I tried to restart it. Apparently the software had managed to damage the system in some way.
The solution is a bit annoying, but works:
Step 1: Reboot into safe mode.
Step 2: Complete the installation.
Step 3: Uninstall the software.
Step 4: Reboot.
I’m still trying to find a decent firewall for Windows 7, but the ones I looked at were not yet 64 bit compatible. Fortunately, Windows own firewall is compatible.