I managed to temporarily resolve this by a sys-restore. Oddly if I run DXDiag it tells me the date of the driver
for my graphics card (HD4850) is dated 2009 !
Even though I've just downloaded and installed the latest up to date version !
Anyway, def a pain in the **** is D.E.P. ...!
Regarding 'I have AVG paid anti-virus and I scan with Malwarebytes and Ad-Aware regularly' ?
Install Security essentials !
No more 'premium' virus protection that tells you everything and yet, does nothing but tie up system resources, carry out scans that do nothing and couldn't detect anything worth detecting other than possible false positives to make your purchase seem sort-of 'justified' !!!