No, I meant your browser - do you use Windows Explorer, Firefox, Opera, or what? I'm not familiar with Windows 7.1. Did you mean Windows 8.1? The operating system doesn't really matter, but the browser does. It sounds to me like this site thinks you are a Linux or Mac system or your browser, for some reason, is reporting to the site that you are. Try cleaning out your cookies for this site. You will have to re-enter your username and password, but maybe the correct CTRL-C and CTRL-V shortcuts will come back.
EDIT: You might also check to see if you can cut and paste OUTSIDE your browser (like open a test text file and enter, cut, paste, some keystrokes). THis will verify that you CAN use those shortcuts, but the site isn't letting you use them.
~Tom