In my experience almost all software producers instruct the end-user to disable firewall and anti-virus and spyware protection before installing - they also tell the end-user to make sure that no other software is running.
WESAYYSO, I understand your frustration, but I'm sure that the Vanguard software has been virus checked so your issue is probably not there - perhaps you mistakenly visited a suspect website before, during or after the install whilst your protection was disabled?
Virussus (virii?) happen even with virus protection and firewalls installed and operating - I wiped out my desktop just before Christmas simply by opening an email that was sent to me by my sister - the email and it's attachment had been checked for cleanliness by McAfee (constantly updated and contantly running, even during software installation). This not only proves what Dave says about computers being only human, it also shows that virus protection is only human and more importantly that humans are usually less than human.
The fact that you managed to wipe out a total of THREE computers is very unfortunate - most people would investigate further after the first one was disabled instead of going ahead and attempting to install again. Almost everyone would simply STOP after the second bad install and think again or ask for assistance. I don't think it's morally possible to lay blame on a software producer for an end-user being careless enough during an allegedly doubtful installation to take out 3 different computers.
I also don't work for X10. I also have been disappointed by their lack of customer service. I (and many others on this forum) also avoid their website. What I have found is that this forum, which is hosted by X10 and operated by devoted users of X10, is a VERY informative place to visit. However, it's probably hard to visit and make intelligible comments if you completely run out of computers due to continuously and blindly following what you believe are defective instructions to install what you believe is defective software.
$0.02
Have a wonderful day and don't forget to return your 'defective' X10 stuff for a full refund