Many programs, including µTorrent, are packed to save filespace and/or deter reverse engineering. You must unpack the the binaries before you can edit their resources. Fortunately µTorrent uses UPX (foss) which can be unpacked by running "upx -d utorrent.exe". http://upx.sourceforge.net/ But editing the binary is unecessary imo in this case, µTorrent lets you place ico files in its settings directory or program folder when run in portable mode to change the main icon, tray icon, and also supports custom bmps for toolbars etc. You can also change the icon a shortcut to the program uses. This is preferable imo because it will save you work each time µTorrent is updated. http://www.utorrent.com/faq.php