McAfee Antivirus.
Got so tired of the software slowing down the computer and freaking out over non-virus programs. Also the price to renew was stupid.
No need for AV running 24/7 on Linux.
After using a few different distros over a couple of years I decided to never go back to Windows (and I detest Apple so that will never be an option), and I settled on Kubuntu.
So. Damn. Happy.