DirectX7 and Windows 10 UAC
This is an obscure post that I'm sure no one will ever have this problem except for me playing Ragnarok Online which uses DirectX7. There is a certain problem with programs that uses DirectX7 on a Windows 10 machine. Obviously, Window 10 was made way after, but there is bug with the User Account Control prompts.
Apparently, if any UAC prompt occurs (regardless which program produces the prompt), all directX7 function will cease until the program that uses it become active again. This means if you alt-tab from your game and produce any kind of UAC prompt, the game will stop rendering. The strange part is that the CPU usage stays the same as the program continues to run. I have confirmed that the directX7 functions stopped by hooking/proxy the functions to a basic logger. I have no idea why this occurs and I'm too lazy to figure it out. Just wanted anyone who comes across this problem see that its not them, its Windows 10 UAC.
Why did I come across such a situation? Because I rely on proxying directx7 to enhance ragnarok online and some features are critical to be run actively. If directx7 fails to run, my proxy functions fails thus needing a new way of running custom code.
If anyone digs deep into this and finds the cause, shoot me an email.