That's an interesting take too Darth Shiv because about a week before I had the problem I installed BioShock Inifinite for a bit of a play. That's a very large game 16GB. It wasn't a simple link between playing the game and experiencing the problem as the problem was present in regular usage, in fact the problem only occurred in regular usage but still "somewhat" coincidental given Darths insights. Who knows what these "optimizers" are actually "optimizing"..... if they get the profiling even slightly wrong it may have significant effect. And for about 2-3 days I guess my usage patterns would have differed quite dramatically while I played in spare time. Then 3-4 days later I had problems. Probably nothing. possibly something. Will also note that the disk in this machine is a seagate hybrid with small SSD and larger magnetic drive.