Whatchya got going on there most likely is the result of a coding error in the app you're trying to download and install - prolly having to do with the installer for that app; NSIS is the open-source NullSoft Scriptable Install System
, commonly found in association with amature-developed software.
A possibility is that your download of the app in question is corrupt, which easily can happen if you're using a download accellerator. Another possibility is that something else you've previously downloaded and installed is affecting the ability ofm NSIS to do its job, which is to install an application.
The "NCRC Commandline Switch" you mention isn't anything you can download or locate, its an error-check inhibiting parameter which can be appended to the command line install string for the app in question. From the Command Prompt , the desired command string would be typed, then the string "/NCRC
" would be typed as the last entry on the command line, then the command line would be executed by hitting ENTER. There's a reason "Not Recommended" pops up in reference to that, and frankly, not to be mean or anything, but if you are not familiar and comfortable with command line operations, you have no business concerning your self with them, and doubly no business using optional switches to modify the intended function of them. If you've gotta ask, you have no need or reason to know.
My guess is the app you're concerned with somehow is related to P2P filesharing, was written by someone of uncertain credentials, and prolly is something you can do well without if you are unable to sort out its problems and pitfalls on your own.
The short version; I recommend you forget about it and move on.