Problem Reinstalling Delphi 10.3.2 (Community Edition)

I was a previous user of RAD Studio XE2 Pro, running under Windows 7.  Recently I purchased a new computer running Windows 10 Pro Version: 1809 and a month ago I installed Delphi CE.  For a couple of weeks it ran perfectly then, for no apparent reason, the IDE failed to open.  On opening Delphi, the opening panel displayed for a few seconds, then nothing.  Windows Task Master showed that no Delphi Application/Processes were active.  Failing to find any information on the Net, I decided to reinstall Delphi CE.

Reinstalling did not complete and resulted in 'Operation error'.  Closing the error panel, a degraded version of the IDE opened.  (Most menu items were missing and New/Existing projects could not be Created/Opened).  Opening Delphi re-started the installation programme, which continued to abort with the 'Operation error'.  However, I found that persistently opening Delphi and re-launching the installation programme eventually resulted in a successful install.  I suspect that, files or registry entries left over from the XE2 uninstalling process were somehow finally ignored and installation completed.

Initially I selected all the multi-platforms options, but I in order to keep things simple I just selected the Windows 32-bit option - it was this that finally installed.  Now I have a working IDE, I use Tools>Manage Platforms... and select all the options.  Result 'Operation error'!  Even selecting just the Windows 64-bit option fails to install.

So, there are two problems.  Why did Delphi CE fail in the first place and what causes the 'Operation error'?