HTML code all jumbled in notepad after download

[nexgraphics]

Question, I am in a real bind with a web site I am working on. Every time I download an html page from the web through th ftp to my computer, it opens up fine, and in proper format, but if i make a "single" change and hit "save", all of a suden it jumbles up all of my html into one huge paragraph, and makes it impossible to do further editing.

Does anyone know why this is happening?

Thanks,