Hmmm - that's a very large text file
Along the lines of what SD has suggested, check that the larger file doesn't have some "hidden" characters or data hiding way past the end of your primary information. It's a very remote chance but with a simple processor like Notepad, that can sometimes happen.
I've encountered this when stripping satellite keplarian elements of spurious text information prior to uploading them to a prediction program.
FWIW
F-O-R