An nfo file is like an advanced text file.
Search for an nfo on the system, R-Click on it and "open with" .. (check the box ... "always use the selected program .... ") Notepad ... to view.
This is a result of someone clicking on an nfo file when Windows does not know what to open it with. So it thinks it should use the System Info Tool to open it .. .wrongly!
Do as above until Windows always opens it automatically with notepad.
There are dedicated nfo viewers available. Not necessary tho. : )