For some time now I had Smart Security v4.0.437.0 installed, and I found that this version slowed down my computer tremendously and also crashed occasionally while the CPU usage was regularly at or close to 100% during an on demand scan, which took hours to complete and even stalled the computer, so that I had to re-boot. As last week an updated version of Smart Security v3.0.694.0 was released, I decided to remove version 4 and replace it with that one. This made a great deal of difference, and my computer is now running normally again and the on demand smart scan completed in 56:02 minutes compared to over 5 hours in version 4 using identical settings. So I’ll think I stick with version 3 for now, as it uses the same updated modules as version 4, so I presume that I should have the same protection except I’m missing the additional components added to ver.4, which I was not using anyway. Just for the record my operating system is Windows XP Pro SP3 and the CPU is Intel Celeron 2.40 GHb, 766 Mb RAM.