There is a chance when downloading the latest version of Defraggler that your anti-virus program will flag the installer for Defraggler to contain a Trojan, and/or a Virus.
This is a what we call a "false positive". Meaning that there is actually not a virus inside the program. It's usually caused by the Google bundle that is inside the setup file. The issue is usually fixed within 24 hours.
There is some thing you can do to fix the problem too. If you receive a Trojan/Virus warning when trying to install Defraggler, please report this "false positive" to the company in which makes the anti-virus program you use.
Thank you for using Defraggler!