First of all, when it comes to virus/trojan/malware removel, all advice is given on a generic basis. Without knowing specifically what is wrong with your PC, this is only a best guess and may not cure your specific problem. There is a presumption made that you are also running a good anti-virus program and have both kept it updated and run regular "complete" scans.

There are three things I would try:

1) Download Malwarebyte's anti-Malware package, update and run it. (I think this has already been suggested). Delete any problem files it finds.

2) Download "Superantispyware" (yes, it's actually called that tacky name, but make sure that you get this specific one - available at www.superantispyware.com). Download it, update it, run a "complete" scan and delete anything it finds as a problem.

3) Go into your web browser's "options" or "configurations" tab (you didn't mention which browser you're using) and reset it to the factory default setting. Make sure your homepage is something benign like www.Google.com. If this doesn't work (because your browser is hijacked, for example), try to download the latest browser version compatible with your operating system. Then uninstall your current browser. Reboot your PC and then install the downloaded browser.

Hopefully that will cure the issue.

Jeff