I had a similar problem a few days ago.
After downloading a freeware software called Freefilesync, Binkiland hijacked all my installed browsers (IE, Firefox and Chrome). In addition, my computer screen turned black for about one hour after each restart. I reset all browsers and uninstalled the programs Binkiland had infected my computer with. The problem with the black screen didn't go away. Avast was of little help.
Eventually, the anti-adware tool ADwCleaner recommended here did the trick. Everything's back to normal now.