>>16
Oh, well, EXEs changing is indeed. In that case you might want to have it checked. Since I was tl;dr and you actually had a reason to post that I'll try to help.
My Firefox.exe is from version 1.5.0.3 and it's 7172197 bytes. It's MD5 digest is 11339f055f44fb9d09e356f04e4a656f .