few days back i was downloading something from internet after the download finished my pc isn't working properly. Everytime there is a message asking me install some software and some of them have installed themselves automatically. Now when i am trying to type anything the windows explorer stops responding and crashes.I thought about installing an antivirus but i am unable to download anything on my pc as the browser just crashes. I already have Microsoft Security essential installed but that's not working. Any advice? thanks in advance.