When copy-pasting in Windows, sometimes the clipboard bar appears, and if you’re really “lucky”, it also pops up a waring, distracting you from your work. The clipboard holds only 12 items, and I have never met anyone who used more than one. There is no way to turn this irritating feature off, unless you want to use the dreaded registry editor.
Feeling brave? Follow the instructions at http://support.microsoft.com/kb/207438.