Do you have an article which won't "Close" or "Save" when editiing?  Do you sometimes prepare content for your website in Word?  This may be the source of the problem.

This happened for one of my clients.  In investigating why, I discovered a (hidden) line of code specifying style which contained invalid character strings.  This confused the editor to the point it was unable to function.

 To correct, do the following steps:

1. Highlight all text (avoid any images). 
2. Right click, then click on "Cut"
3. Next, click the editor icon that looks like a clipboard with a "W" on it
   When you hover over it, "Paste from Word" appers
4. In the pop-up, right click, then click on "Paste"
5. Click "Insert" at the bottom of the pop-up

If you have images in the middle of the text, you can repeat the steps above for each section of text.

Note:  you may need to add back any formatting which might be lost, such as font color and size.