Editor problems in File Manager
If you experience problems with File Manager when you try to edit a file this is due to the character page setting in your html file.
Try turning off the auto detect setting and choose the character setting you believe your HTML file was set as.
The Editor is following HTML standards and if you have not followed these standards it will not load the page.
Adding this line to your page may help
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
utf-8 is the suggested setting by those that set the standards.