I was getting this error after the new version was installed... here's the error in full: An error has occurred. Please report this error code to our support team. MBAM_ERROR_UPDATING (122, 0, MultiByteToWideChar) The data area passed to a system call is too small. One time I also got this: MBAM_ERROR_UPDATING (404, 0, HTTPStatusCode) The people at support.com helped me fix this. They remoted controlled my computer and fixed it for me. They said you can copy the update file from a working computer using a flash drive or CD onto the computer with the issue. I had a laptop with Windows 7 and my XP desktop was the system with the issue. For Windows XP and 2000 you can find it at C:\Documents and Settings\All Users\Application Data\Malwarebytes\Malwarebytes' Anti-Malware\rules.ref For Windows Vista and Windows 7 it is stored here C:\ProgramData\Malwarebytes\Malwarebytes' Anti-Malware\rules.ref