Thanks for the reply Vlk,
Part of the problem is that the task bar is the 1st thing to freeze up (start button and system tray icons all non responsive) so it's difficult to tell if the scanning engine is still working in the background.
I can say that WLM experienced no problems with the version 4.7.942 (and from what I can remember ,4.7.981, as I don't use it much on this PC)
WLM and overall system config hasn't changed.
Thx.