After installing the updated NIS to 22.5.0.124, on opening Outlook 2013, Outlook started to issue message (see attached PDF snippet) :-
There is no default mail client or the current client cannot fulfill the messaging request....".
I went and made Outlook 2013 the default program (it was anyway), but that made no difference.
Since the Norton update, I now notice that there are also MANY entries in the Windows event log saying:-
Detection of product '{9AC08E99-230B-47E8-9721-4577B7F124EA}', feature 'OutlookMAPI2Intl_1033', component '{BC5551FA-8420-403D-99D7-1EAC191169EA}' failed. The resource 'C:\Program Files\Microsoft Office 15\Root\VFS\ProgramFilesCommonX86\SYSTEM\MSMAPI\1033\MSMAPI32.DLL' does not exist.
and
Detection of product '{9AC08E99-230B-47E8-9721-4577B7F124EA}', feature 'OutlookMAPI2Intl_1033' failed during request for component '{BC5551FA-8420-403D-99D7-1EAC191169EA}'