Hi, Jeff 

I don't have a test url as the editor is only in our dev enviroment. I can share my screen of our dev enviroment through join.me if someone from support would do that.

Point 1: Cleared the croswer cach but still has same effect. I'm using SiteRelative paths, here's an example of the img src:

admin/content/Web/Resources/Image/ALFALogoWhite.jpg.

When I drag and drop the same image into the text editor I get:

 /Web/Resources/Image/ALFALogoWhite.jpg and it shows up.

Point 2: yes, the text file was opened on the server side.

Any ideas on point 3 from my original post? 

Update ofr point 3: the dialog for insert hyperlink is not missing but it is trying to open defualt.aspx instead of tag_a.ascx. This is happening for many of my dialogs...