While this most likely isn't relevant to your specific issue, since directx problems can mean a thousand different things these days (and it seems to be windows default message lol), but if anyone is getting the directx crash randomly, or especially when specifically approaching certain errors, it is most likely not your machine or graphics set-up at all, but instead just a simple glitched/missing dat file.
This problem used to drive me up the wall, and after weeks of messing with game setting/directx, trying different cards and driver versions, I realized it was just one or two messed up game files. A fresh reinstall fixed so many problems
I hope this helps at least one person out there one day! but sorry for your problem OP I am not at all familiar with isolated windowed mode issues. I actually get more problems when running full screen lol
