Translation Memory and Document Settings screen problem

Hi  I have had to reinstall Studio 2017 following a reinstall of Windows 10 and have run into a problem.  When I use the 'Translate a Single Document' option, the 'Translation Memory and Document Settings' window opens and allows me to choose the language pair, etc.  However, for the next document I try to open the TM selection options, etc part of the pane does not open - the window will not respond to any further input but I can close it and return to the normal screen, so Studio is not frozen.  This is what the screen looks like:

I have found the workround of deleting the BaseSettings, Plugincache and Usersettings XMLs in the AppData which allow me to reload and re-initialize Studio and get the normal 'Translation Memory and Document Settings' window again, but obviously I don't want to have to do this for every new document I open.  Anyone run into this particular problem?