have you updated windows?
check for spyware and virus in your system.
if you can do a bootup scan for viruses or do it in safemod run the antivirus scan from there most software will still work in safemod as for scan type software like anti-adware and anti-virus. there they can hide at all
did your system crash like a power outage some time in last 2wks
keep in mind some sites (not all) will hijack your browser so it will not leave the site you came across! when it seem to hang or lockup or the back button don't like to work right, always going back to the page your on and not going back to the page you was on before you got to that page.
Spybot-S&D you can find it lookup google to search for it, its a anti-adware software will remove a lot of bad things in your system, you can download it from many sites out there.
think it from
www.spybot.com check it out
download page link:
http://www.download.com/Spybot-Searc...spybot&subj=dl