@Brian Lancaster: To be honest I have no idea what may have caused that issue or how it was resolved. As has been stated a memory corrpution seems like the most likely cause. Still, it must be one hell of a memory mess-up that will carry over into VRAM (without triggering an access violation first) and that without more serious breakage than that.
As for the Windows 10 Creator's Update, that indeed seems to have been causing issues for lots of people, and not only pertaining to DBPro but more DX in general. Unfortunately I haven't really been able to investigate this, ironically because I was forced to reinstall my OS and apparently Microsoft has decided to not allow activation of old OEM Windows 7 keys anymore, thus forcing me to get Windows 10, which has stripped out a lot of development tools for anything below DX11. I'm hoping to get around to getting my build environment going again eventually but it unfortunately takes more time than I've been able to spare lately. But one day...
I wonder if the new "Creator Fall Update" may have resolved anything on the off chance Microsoft would consider themselves having broken any backwards compatibility with that latest update. Not likely but will be interesting to see nonetheless.
Brian Lancaster wrote: "... but it works fine after a short mysterious blank blue screen if I run it on 1024x768."
Have you tried it with something that doesn't just draw a static image (ie. try moving the image back and forth, rotating it, printing the current framerate or something)?
I have a feeling it just draws one of the buffers in the swap chain and you happen to get the second one which has already been rendered to there. Or possibly if it only renders to one of the buffers instead of each one (that should yield flickering unless it also only displays one / a subset of the total though or your framerate is a perfect multiple of your monitor refresh rate).
Green Gandalf wrote: "I haven't found a way of getting Synergy to set the compatibility mode in the editor."
The compiler could be made to do that, assuming the editor won't overwrite it after.
Brian Lancaster wrote: "I don't think I'm going to use 9Ex, because I just timed the loading screen, and it takes nearly twice as long to load each level. (EDIT: Because of loading images)"
It shouldn't do that. Are you using the
ENABLE VIRTUAL TEXTURE MANAGEMENT command or creating your images using a third party dll? In that case it can take longer as it has to allocate backing texture copies in RAM, but if not it should if anything be faster as those copies (which are created by default, however it is a built-in feature of DX9.0c so quite probably more efficient than the hacky function call interception method I have to employ, in the official DBPro versions) are not created or synchronized.