libmmd.dll is a dll file needed for Cinema 4D firstly and some other programs on your machine.
It's needed for some special functions inside the programs.
Usually this files are installed automatically with Cinema 4D.
If the file isn't saved correctly from the system or has been modified by another program it could cause problems.
- You're actually missing two DLL files: libmmd.dll and svml_dispmd.dll; sometimes these files are lost by Windows for a multitude of reasons. Fortunately this problem is common enough that these DLL files come packaged with your installation of Cinema 4D just in case you need to replace them. Just go to C:\Program Files\MAXON\Cinema 4D\resource\libs\win64 and copy the libmmd.dll as well as the svml_dispmd.dll from here into your C:\Windows\System32 folder. Once you do this try launching Cinema 4D again; it should now launch normally.
- If the problem persists after trying 1 and restarting the computer, please search the file on your computer. Usually the file is located here:
C:\Program Files (x86)\Common Files\Intel\Shared Libraries\redist\intel64_win\compiler
Delete the file and restart your computer.
Open the folder "\bin\data\redist\" on your Cinema 4D installation media and
install the file "ww_icl_redist_intel64_2016.4.246.msi".
After restarting the computer again, the program should run properly.
As this program is used in different versions from different programs, the version can change from time to time and cause such problems starting programs.