Random guess. You are being bitten by character encodings.

Different applications in Windows use different character encodings. When cutting and pasting between them you will find that Windows silently changes the actual data to be what is closest to being displayed in the same way. To see this in action, print a file to a command line, and view it both in an application that runs in the command-prompt (eg edit, or just print it out with Perl), and one that is Window based (eg notepad). You will find that é in one is not in the other. Play around with cutting and pasting between them, and with chr and ord to get a sense of what is happening.

If you don't know how to cut-and-paste to a terminal, try right-clicking on the title-bar of the command prompt and follow the menus.