cannot open avg antivirus 8.5

Ok, so I've been having this same problem for quite some time...I go to even search AVG antivirus to install it on my computer, (heard about it from several friends) and I go to search it, and my computer automically like knows where Im trying to go, and the whole page just disappears.. also I have another problem, recently my 10yr old was on his normal gaming sites, and "Accidently" downloaded Personal Antivirus Protection, and well finally I got it out of my computer, but still when i go to certain websites it will go the webpage momentarially, and then redirect me to a "Blocked" page that says the page Im trying to visit is infected and gives me the option to download the Personal Antivirus Protection again on Go on unprotected, however, when I click on go on unprotected, it goes back to the webpage I was trying to view in the first place, then goes right back to the blocked page. Can ANYONE help me???