It sounds like you got with some adwares where you may want to run a pair of free programs that have been shown effective repeatedly. For adwares, browser hijackers, data miners(track your browsing history-generates spam) grab the free AdAware SE Personal found at
Lavasoft For an excellent free antivirus utility that can even alert you on trojans even when disabled from the startup list AVG 7.1 Free edition can be downloaded free at
AVG Free Advisor: AVG Anti-Virus Free