c1_sh.dll is a DLL file, and it belong to a software program belonging to the Microsoft Visual Studio. If you want to create applications, then you might have this program on your computer currently. Developers of applications use it most often. If you are trying to run an application that is a part of this program, and your directory tries to open this file but is not able or has somehow become corrupted, then it is time to fix the error or errors associated with this file.
This can be done easily with a quality registry cleaner. An excellent choice in registry cleaning is ZookaWare PC Cleaner. It is a relatively new product from ZookaWare. Blue Penguin also makes SpyZooka — the increasingly popular spyware remover. If you want your errors cleared fast, then ZookaWare PC Cleaner is the choice for you.