Or
After moving the content Editor webpart , when we click Exit edit mode . It gives "Unexpected error has occured".
Resolution: Open the Site in Firefox\Chrome browser as IE will not give you the Drop down to edit the webpart
Modify the Content Editor Webpart
Open the Source Code
Remove the following Tag from the code for eg:- "id=WebPartWPXX WebPartID="XXXX-XXXX-XXXX-XXXX-XXXXXXXX"
Click Apply - OK
You can then move the webparts without any issues