It may not have been anything you did wrong. With the latest version of Hackman (8.0), the freeware version has a fairly low limit of the file size it will handle (something like 200KB, IIRC). I would have assumed it would not open larger files, but maybe it simple opens the first part of the file. Sorry I didn't mention this before; when you said the offsets were displayed differently, I assumed you had a different editor and didn't think of it.
For anyone else needing a hex editor,
Frhed is an open source program, though has not been updated in awhile. Alternately, check this list of
freeware hex editors.
