Some more information, looking at the Windows 10 Event viewer, the following app error is reported when lightroom starts:
Faulting application name: lightroom.exe, version: 126.96.36.199, time stamp: 0x56a2e8ef
Faulting module name: MSVCR120.dll, version: 12.0.21005.1, time stamp: 0x524f83ff
Exception code: 0xc0000409
Fault offset: 0x0000000000074a30
Faulting process id: 0x1d30
Faulting application start time: 0x01d1668443f8db27
Faulting application path: C:\Program Files\Adobe\Adobe Lightroom\lightroom.exe
Faulting module path: C:\Program Files\Adobe\Adobe Lightroom\MSVCR120.dll
Report Id: 2f3a82a5-462b-4db4-bd1d-7637b780e57d
Faulting package full name:
Faulting package-relative application ID:
I have downloaded what I believe to be the latest 64 bit MSVCR120 package from Microsoft, restarted, but no difference....
So what version of Lightroom do you really have installed. Your error log indicates that the faulting application is Lightroom 6.4. Lightroom 6.4 and Lightroom CC 2015.4 are licensed completely differently.
I am using the Lightroom CC 2015.4, have uninstalled it and re-installed from the CC App.....
Morning all, just thought I would update this thread. this morning, Adobe CC launcher app updated..... and bingo, Lightroom now functions and starts correctly...... Thanks Jim for your interest.... hope this helps someone else out. looks like perhaps all the Apps are interlinked and update each other? but what do I know, I am a hardware Engineer ;-)