If MalwareBytes installed correctly, go to its Program files folder, find the mbam.exe file, and rename it to something else, eg something like gogetum.exe . Make sure you include the .exe

Then double click that file and it should open. Update it's malware definitions, then run a scan.

If that doesn't work, try it in Safe Mode.

If the link sends you to a random place, Safe Mode is Windows XP loading up with only generic drivers, eg no special features. When you restart the computer, and when Windows starts to load, start pressing the F8 key once a second until you get a black screen with a list of Safe Mode options. Select "Safe mode with networking" as you will need to start MalwareBytes and update its definitions, then perform a full scan from safe mode.