This file (in the bin sub-folder) is installed along with the cvi runtime engine and contains the library error strings for certain CVI libraries like ActiveX, DataSocket, Toolbox, etc. Basically, the libraries use this file to publish and lookup the error descriptions for library error codes - sometimes other CVI and NI programs may also use this file to read the description for a particular library error code. This file is part of the runtime engine and does not contain any information about user's programs, etc.
Yes, I know. cvierror.txt is NOT a log file and has the same contents on everyone's machine. It is not meant to provide error information to you, the user. It is only meant to be used by the cvi runtime engine components to look-up error descriptions from error codes.