I still don’t know what the root of the problem is but I’m thinking it has something to do with the DirectX dependencies that get installed along with the game. I upgraded to Windows 10 a couple of days ago and haven’t really encountered any problems as yet. Open Broadcaster seems to be having issues encoding the video properly so I’ve taken a break from streaming everything I play while I look into that.
I only did an upgrade of Windows rather than a fresh install as it seems that is required first time for WinX and I had assumed that would cause me some annoyances as an upgrade often seems to do a sub-optimal job of implementing the new system on top of the old one. I was therefore fairly pleased that nothing much seemed broken after updating.
I saw a couple of friends playing CSGO this morning and was considering installing it again just on the vague chance that something about installing the new OS would un-jinx it. Eventually I decided I ought to see what happens, downloaded and installed the game and, upon running, got the pop-up window showing that the DirectX dependencies were being installed.
It finished that and the game appeared in front of me blaring the default volume menu music out of my speakers. I was fairly surprised and hadn’t been expecting anything to change so I didn’t actually play any. I will clearly have to check it again shortly to see that this isn’t a fluke.