Disappearing text and code?

I was using notepad to write the code and text, for my website and then would cut and paste it into the editor under "source" the code worked fine on the web site but when I went back into the editor to make some small changes, the code on the source end of the editor was blank, it all just disappeared, but the text is still fine on the web site? This only happens when I cut and past code and text together from Notepad. If I just past text and add the additional code in the editor I'm fine.

I am hoping someone else has figured out a way to cut and paste code into the editor using Notepad or another program! Please let me know what I can do to fix this issue.

Thanks
Mark