|Restart in Safe Mode with Networking. Download, Install, Update, and Run Malwarebytes. Remove all it finds.|
Run a Manual Windows Update (still in Safe Mode), install all Important and Security Updates as well as anything associated with Internet Explorer.
Restart in Normal Mode.
Do a Disk Clean Up.
Uninstall programs you never use, especially if it is something you did not install. Google the names of anything you are not sure of to help you decide.
In your browser, disable all add ons and 3rd party toolbars.
In your browser, Delete all History, Cookies, Temp Internet Files, etc.
Set your browser to Delete Cookies upon closing.
Set your browser to keep History for only 2 or 3 days.
Install another browser of your choice (Firefox, Chrome, etc), In Safe Mode with Networking if still it does not install normally.
You have to be a little bit crazy to keep you from going insane.