Ok, may have found the issue here - I'd tried everything to get this working, all the instructions on the forums so far, but nothing was working. What I've finally done is change my monitor and for some reason it's started working, which makes me think it was an issue with the original monitor (some no-name second hand jobby) not reporting itself to the graphics card properly and the GPU therefore not enabling certain display features (not sure what those features would be - hardware acceleration? DirectX?). I've plugged a borrowed Dell monitor in and it's now working as expected. This would also make sense with some of the other tests I did such as trying Remote Desktop to see if I could see it from another machine, which was also failing before but which now also works. Just thought I'd let people know in case anyone else is having the same issues still. (You could probably get a dummy display adapter for a few bucks and see if it starts working through something like Chrome Remote Desktop if you wanted to test, rather than shell out for an expensive monitor replacement.)
