How to get rid of the "msiexec.exe" thing?

msiexec.exe is not a virus, it's the windows installer that installs programs... a virus may be using it somehow, but you don't want to get rid of it... you want to get rid of whats using it. if you have malwarebytes and it isn't detecting anything then I would probably start with downloading the newest version, uninstalling the old one and installing the new one, updating the definitions and then booting in to safe mode and running a full scan.