The file MSVCRT.DLL in the SYSTEM32 folder is a protected file, meaning
Windows does not want you to replace it or it could cause instability. Post
more info, why do you want to replace it? Where did you get the version you
are trying to install?
If you think it's corrupt, try running "sfc.exe /scannow" and Windows will
check the protected files, replacing any that are corrupt or have been
replaced.