msmc.exe definition, relationships, removal:

msmc.exe is an executable file that starts a malicious process, launches certain parasite components or runs a destructive payload. Even if the msmc.exe file does nothing suspicious, its presence indicates that your computer is infected with a particular threat.
The msmc.exe file is installed and used by browser plugin ClientMan.
The msmc.exe file usually runs the same named process. This process silently works in background and performs harmful actions. It remains active while msmc.exe is present in the system. Removing the file will immediately terminate a process and prevent it from running later. That is why you have to manually delete the msmc.exe file. If you cannot erase it, consider using recommended spyware removers, which will get rid of msmc.exe and associated parasites for you.
Please note that the msmc.exe file actually may be a fully legitimate part of the operating system or legitimate software. Often parasites use files with unsuspicious names, but malicious functionality. You should always carefully check the file before deleting it. It may not be related with malware, but can be required by your essential programs to work properly.