The file c1_sh.dll is part of Visual C Compiler Front End from Microsoft Visual Studio.  A compiler is what turns human-readable computer code into machine language computer code.  If you are not running Visual Studio, this file usually won’t be sitting on your computer.  However, because it is a dynamic link library, there is always the possibility that another program is using the information the file contains to do its work.

Dynamic link libraries are chunks of computer code and other information that assist programs to do their jobs.  The registry of the computer keeps track of where all the dll files are located.  If the file is moved, overwritten, or corrupted somehow, the registry may generate an error listing the file.

To fix the error, you can try to move the file back to where it belongs.  The trick with that is finding where it belongs.  You could edit the registry, but that isn’t a good idea unless you are an expert.  If you make a mistake, you could disable your computer.  Or you could run a registry cleaner, like ZookaWare PC Cleaner, which will fix the problem for you, guaranteed.