I have also experienced this problem. I could not paste anything that I had copied or cut,(and I tried the right-click menu, the edit menu and the shortcut keys, (heck, I even tried the old ctrl+ins, shift+ins).
I suspect that the clipboard had just had enough for whatever reason, because a restart fixed the problem.
If it happens again, I might just try going to task manager and killing and restarting explorer, I suspect that will also resolve the issue.