Sounds to me like you have an adware problem. The first thing I'd do is run a program such as MalwareBytes to check your comp for malware.
The next thing I would do, is stop using internet explorer, because it's a pile of shit. Chrome or firefox would be your best bet.
If you insist on using internet explorer though, check to see if there are any plugins/addons/toolbars that are there that shouldn't be there. If there are, uninstall/delete them.