My own copy of o2ksr1adl.exe was downloaded directly from MS, too, way back when. It does, as expected, have the properties reported by submix8c, that is: By appending CR,LF (0x0D,0x0A) bytes to the end of o2ksr1adl.exe, with a hexeditor, it grows by two bytes and then presents the following properties (exactly as reported by Peter): So the file Peter downloaded is bona-fide and can be used safely. It's not that uncommon to get files with some bytes appended to the end of the, usually either CR,LF or some zeroes. They cause no harm, nor modify the functioning of the installer in any way. Sometimes, some trailing zeroes get deleted also... And then it's more complicated, because they must be restored by trial and error... Both are part of those mysteries of the internet that are better left alone...