Here's a pic of the error...
This means the mbam.exe was deleted by the malware you are dealing with.
Easy workaround is, download a randomized renamed mbam.exe version from here... http://mbam.malwarebytes.org/program/random.php
Place the renamed mbam.exe in the Program Files\Malwarebytes' Anti-Malware folder on the infected PC and launch the renamed file.
Then malwarebytes should run.
In some cases, it will be needed to rename the random named mbam.exe to explorer.exe (this for example when you are also dealing with "Security Tool" or another fake scanner - you can actually bypass whatever it blocks by renaming the program/ exe file you want to run, to explorer.exe).
Once the renamed mbam.exe runs,
First step is to click the update tab in order to download the latest updates.
Then run a quick scan and let Malwarebytes quarantine what it found.
Reboot afterwards.
After reboot, it could be possible that you'll get some "bad image errors" after reboot, similar like:
To fix this, if you have Hijackthis installed, start a scan, and look under the O20 line where it says O20 - AppInit_DLLs .
It should look similar like this:
O20 - AppInit_DLLs: wisahiri.dll <== filename that was appearing in the bad images error.
Select that entry in Hijackthis and click the "Fix checked" button below.