I have exactly the same issue as DEAMAN, i.e., I successfully installed Extreme Security (after purchase) on a VISTA laptop and have failed repeatedly on an XP/Home SP3 destktop. After a reboot, the system becomes very cpu-bound and spirals to a "bluescreen" coredump. I have used methods on this forum to remove all vestiges of old security packages, redownloaded Extreme --- all to no avail.
However, just today, I read the minimum requirements for Extreme which calls for 1GB memory. My old DELL has only 768MB of memory. It would have been nice if I had been warned about the requirement when I was encouraged to try Extreme --- I had happily been using Internet Security for 2 years prior.
So - could the memory shortage be causing my prob?
Can I download Internet Security for the desktop and use the same license key that I received previously (3 PC license) and is working on my VISTA laptop?