One thing you might want to consider as well.
Some virus makers are aware of malwarebytes product (and others). If it does not work, it may be getting intercepted by the malware, especially if it is a root kit. One solution is to rename the mbam.exe file and run it under the new name.
This would only be necessary if the malwarebytes products does not initially work.
You may need to update the signature file after you initially download the product. There is an update feature.
Also, when you run the scan, make sure that you are disconnected from the internet.
You may have to run the scan multiple times, because root kits sometimes put hidden files that try to restore themselves. The one that I had did this. I actually had to edit the registry to get the last piece, because it was cleverly hidden even from malwarebytes, though obvious once you recognized it (I found info on it elsewhere online).
Do not consider it clean until you have at least two successive runs that come up with nothing. I learned this the hard way.
Let us know what you find.
BrianIs
AtYou