Thank you for your answer, I now managed to run the game consistently without crashing. The only issue I have is that the game either runs on 400-900 fps and therefore is not playable at all or, when I activate vsync, I have insane input lag and therefore is also not playable. Everything else seems to work alright for now.

I just found my CD of POD yesterday and decided to try a bit of time attack after I found this rather not so active community here ;) I already got a WR on Alderon FLAP after 4h of getting back into the game, just to notice that my game is running at approximately 1.3x the normal speed. This can be easily noticed by looking at the live timer in the top right corner, which is obviously running too fast or when comparing my video and times to other videos.

You can see this in my video of my run here:

I don't know how this affects the validation of my run(s), as this makes the game rather harder for me than easier, although I would like to have the same chances as everybody else. So if anyone else has a similar problem or any idea, I would appreciate any help or suggestions. Furthermore I still have a lot of problems running the game, e.g. I can only play in fullscreen, when tabbing out the game always crashes and takes 5+ tries to restart again. I also can not change the volume ingame and not in Windows beacause I can't tab out lol, so it is extremely loud for me.

Thanks for reading, maybe we can get a bit more action into this community!