Can't insert links in Visual Editor

Using purethemes Centum with built in tinymce
When I try to insert a link with the visual editor, I get the dialog box, enter the url , click okay and the entire post is wiped out. Also can’t change Status, Visibilty or Publish.
I tried disabling TinyMCE altogether – it’s not a separate plugin – and then of course the entire dashboard was blank.
Also disabled plugins, etc.
I’m working on a legacy site, so I don’t have access to do a clean install or upload any original files

Any ideas appreciated!