|check your proxy settings, in internet explorer under tools/internetoptions/connections/lansettings.|
if it something wierd looking, remove it.
reboot the computer in safe mode with networking, ( press and hold the F8 key as your computer restarts. You need to press F8 before the Windows logo appears. If the Windows logo appears, you'll need to try again by waiting until the Windows logon prompt appears, and then shutting down and restarting your computer.)
from there go to www.malwarebytes.org and download, and run the free version. let me know how it goes.