Category re-naming crashes Personal Plus 2018

I've edited a Category Name and now its Sub Categories (tediously and painstakingly edited to fix a hierarchy problem I created) have seemingly dissassociated themsleves, plus any attempt to edit the Category Name crashes Perosnal Plus 2018, as does trying to run a saved report . Help! Reckon reports sent, but can't use Personal Plus until problem is fixed - I think I'm in a loop.