Copy/Paste Problems

Hello,
I'm having problems with pasting my code when working in both the design and
code windows. I can copy something and when I go to paste it, it creates a
copy of the page that I'm working on in the site files window. It will not
paste the code or text in the page itself. So for example, if I'm working on
index.html and want to copy and paste something within that page, I will
instead get Copy_of_index.html in the site files with nothing pasted in
index.html itself.

Anyhow, any help at all would be greatly appreciated.
Billie