"The workaround of creating a 3d profile in nVidia Control panel for their version of PowerDirector, and disabling CUDA cores, has resolved the issues for MOST users. This is a temporary fix to allow PD11 and other programs to work until nVidia fixes the problem" - FredB.
Yes, thanks FredB, as I've written, this was a workaround for me, but one of the big attractions of the Geforce cards is CUDA, and having hardware acceleration swayed me to download the trial of PowerDirector 11 Ultra, to take advantage of CUDA. I've been corresponding with nVidia support but they have just made rote suggestions of installing in Safe Mode, choosing Custom Install, Clean Installation, and so on. I've followed all of those suggestions, of course. Cyberlink have so far ignored that I could get PD11 working by disabling CUDA for that program in their driver Control Panel. I've told them that the problem persists with the brand new nVidia driver Version 306.97, released yesterday. Now I’m waiting to hear back.
People like me with the newest Geforce cards that came with driver version 306.23, and not 301.42, are the ones that can’t roll back and thereby use CUDA.
Fred (and others), I wonder whether this really is a nVidia driver problem. Could it possibly be something requiring a patch from Cyberlink? I wouldn’t have thought so, because nVidia have previously released a driver that fully works with Cyberlink’s latest products. Does anybody have a strong opinion on this one question of whether the problem lies with Cyberlink or nVidia, so that users of new Geforce cards affected know who should be pressed for a solution? - Phil