Is this file a legit? Location here: C:\windows\system32\drivers\qdfsdrv.sys.
Properties identifies the file as Norton Filter Driver 7.0.0.15 (Norton CleanSweep). As I haven't had CleanSweep (NSW 2003) installed for years, this file must have been left behind an old NSW unistall .. and has been loaded for no good reason.
At any rate, when I stopped it from loading I regained about 150mb memory. Does this make sense or not? Maybe a coincident related to some other action .. but, as I have been chasing a 150mb memory culprit for some time, I hope this is the one.
Best, CBA