My browsers have recently been plagued by some kind of trojan that always opens up the Wisesearch.com search engine, which is rubbish, and puts annoying adverts all over the place. It pretty much disabled Internet Explorer and Firefox and greatly impeded Google Chrome. Eventually I got rid of it. There were essentially 3 steps I took though whether step 2 was really needed, I don’t know. I would restart your computer after each step.
1. Use the FREE version of Malwarebytes http://www.malwarebytes.org/
This is FREE which is good and spotted and destroyed some trojan software.
2. I used Trojan Killer http://trojan-killer.net/ which removed a bit more malware. This is not FREE. Well it is free to scan but you have to pay to remove the resulting trojan software that is found. When you go to pay they will offer you the 1 year certificate ($39.95). There is a 6 month certificate which is $10 cheaper at $29.95 – every penny/pound/dollar counts!
3. I reset all my browsers.
Google Chrome – Settings – Show advanced settings – Reset browser settings .
Firefox – Orange button (top left) – Help – Trouble shooting information – Reset Firefox to its default state
Internet Explorer – Settings – Internet Options – Advanced – Reset Internet Explorer Settings
If you want to save money I would first try step 1 and then step 3. If still there then try 2 and then 3 again.