If you think Malwarebytes is somehow corrupted, you could try uninstalling/reinstalling it. If it's not corrupted, you could try running it in Safe Mode. It's easy to change the search engine, but the procedure differs between browsers. In Firefox you click the little down pointing arrow where you do the search. In IE11 hold down ALT and press T, then click Manage add-ons. Click the Search Providers, and select the one you want.
If you need more tools to use for checking, you can
Download Junkware Removal Tool and run it.
Download TDSSKiller and run it.
Scroll to the bottom of the page and click the box to accept the EULA and click the START button. Then click the Enable detection of potentailly unwanted applications button and click Start.
Click YES to any popups you get. This will download the virus signature database then scan your system. That will take a good while to run - on my laptop it took about 2 hours, but you can do other things while it runs.
When it finishes scanning, click List Threats. Then click Copy to clipboard and paste it into your next post here.
Edited by wpgwpg, 15 July 2014 - 12:24 PM.