The last couple of days our PC has had problems whenever anything involving video or non-basic graphics were involved. I tried all the obvious things, rebooting first, re-installing the nVidia drivers, then upgrading them to a more recent version when that did nothing to help.
I finally tried cleaning the registry with a couple of different programs I usually use for such purposes. A few minor issues were discovered, though nothing appeared to be related to video. Anyway, the same problems occurred – changing resolutions, switching from DualView to single monitor use (or back again), playing videos or anything using DirectX would often as not cause the nVidia applet to unload itself from memory, and sometimes cause the explorer process to hang.
Finally, I decided to do a proper job, and downloaded a couple of utilities that clean the drivers completely off your computer. Basically you remove the video drivers via Add/Remove Programs applet in your Control Panel, cancel the add hardware requests that will pop up, reboot into safe mode, then run the cleaning utils. Reboot once more into Windows as you would normally, then install the nVidia drivers. Another reboot, and hey presto, my PC was running as it should once more. Anyway, the two (free) utils are called Driver Cleaner and NFR (Nasty File Remover). Ideally one should do the job, however I decided to play it safe, and NFR did find 4 files left behind by the DC. DC is now actually a product that is sold, however the previous free versions can easily be found by a quick Google search.
PS Not a sponsored post, just providing the links in case other readers have similar problems in the future.