WD has only crashed on me three times and on all three occasions I have been away from home
This time there was a screen message to the effect that the clientraw files were corrupted.
Tried to recover lost data from datalogger but the downloaded data missed large chunks.
Being clueless, I closed down all WD then the PC.
On restart, it deleted two lines and reinstalled some other stuff.
All seems OK at the moment. Keeping fingers crossed.