What other security tools are you using? Did you disable them prior to attempting the install? Malwarebytes uses a "run once
" load registry value for the installer to complete the installation. Other security tools which monitor startups may be prohibiting the "run once
" from executing and allowing the installer to complete on reboot.
Malwarebytes Anti-Malware uses Inno Setup
instead of the Windows Installer Service to install the program. As such, you can also try installing in "safe mode
If that still does not resolve the problem, try the SUPERAntispyware scan.