This did it. I had to add a few exclusions and reinstall, but it finally actually loaded just now. Sorry I didn't respond right away, I wrote it off as a lost cause, but I REALLY miss PSO1 so I came back to try again. Thanks for assisting!
I checked the FAQ, and the listed solution was apparently to change the resolution to one that worked. I Tried what felt like all of them and none of them worked. I will say it looked like the Mouse was squished for the second the game was actually open. This didn't change no matter what I did.