Very weird problem, help!

Okay I might have the weirdest problem ever.
I'm helping a friend to make a site, this site: http://lucyreneehq.com/rebecka
It works perfectly fine in Mozilla Firefox and in Internet Explorer 7, UNTIL she edits the code in notepad ++.
Then everything ends up on the left in Internet Explorer and a line appears.
The thing is that it's the exact same code and everything I do to fix it is to copy the code, delete the file and then pasting the code into a new document in dreamweaver. Then I save it and it works perfectly again.

Also sometimes å, ä and ö stops working and then I have to do the same again and then it works.

I'm going nuts!

Make sure n++ is saving it in the right format/encoding.

Validate your page

Page shifting to the left in ie7 is normal.In ie8 it works fine so dont worry, and where is the line you are seeing??

Regards.

Oh okay thank you guys!
How do I make sure notepad ++ is saving it in the right encoding?

I have fixed the pages now and and need to find that notepad ++ solution and then tell her. Thank god IE8 doesn't have that issue.
I'm so sick of Internet Explorer right now.