Windows 10: Whatsapp will only load once after booting

Apologies if this is not an appropriate place for this but Whatsapp is an App!
Windows 10 - latest download.

Earlier today whist indulging in some graphic editing of a large file I had a BSOD. It's not that I am querying; it is the result it had after re-booting.
I needed to play an MP3 file - it wouldn't play but it would play on Audacity where I had produced it. It was the resulting MP3 that wouldn't play. I tested with other apps and found that none worked and Media Player wasn't working either so none of the CDs I have on my PC would play (for convenience - I own the originals!).
The other problem I found was that Whatsapp wouldn't load.
I re-booted (powered down) and since then Media Player and other players all work fine and can be opened and shut down without issue.
However WhatsApp won't oblige. Post re-booting it loads and works. Close down and try and re-load and it won't load. I have to reboot first.
I have tried reinstalling over existing installation, uninstalling and re-installing afresh, but neither solve problem.
I am at a loss as to where to look for possible causes next!

:)