I upgraded from Windows 7 to 10 a few weeks ago. No problems for the first couple of weeks but now I have a really annoying glitch where programs that I am using randomly lose focus for a moment, sometimes to the extent of flashing rapidly. All programs are affected but explorer.exe seems particular prone to the flashing.

I downloaded the Happy Droid focus.exe utility to find out what was taking the focus and it turned out to be the Desktop Window Manager system process!

I have updated the graphics driver (Intel HD Graphics 4600 integrated) to the latest after a BSOD that was traced to the driver, but still have the focus glitch. All updates have been applied from Windows Update.

I'm at a bit of a loss as to what to do next! Any help much appreciated.