AVG Security Software Created havoc on my computer to try to get me to buy other software internet

I downloaded AVG free after deleting Webroot after it shut down my computer when I wouldn't renew their antivirus suite. Soon after downloading AVG I began to have problems with my screen going black, my computer slowing down and hanging up. I then got box that said that AVG had detected a virus called TrojanDropper. I did a web search and discovered that only AVG is identifying this supposed virus and that it never seems to go away. There was one website recommended to "help" rid my computer of this virus which, of course, would cost money. I tried to delete AVG after smelling this rat but at first had no luck. I shut down my computer, brought it back up and then deleted it. I have since downloaded another antivirus software. I then found out that Google had been having problems with AVG as well and read several similar complaints about AVG from other users. This seems to be a new trait amongst some antivirus developers to force users into paying for their crappy software.