@calvorejas I'm starting to think that it might be a hardware problem...
Because I restarted multiple times and by wiggling the sticks (it's a homemade arcade machine) before launching any game, anything, it seems that the problem disappears... But I don't know for sure if this is possible... I though I broke something software related, but now it seems it has to do more with hardware than software...

A bug I have always encountered is that sometimes... My right stick gets stuck like it is being push to the right... And I have to wiggle it so it stops being permanently pushed... Although, the stick is not being physically touched or pushed to the right, it's not even broken, the microswitch that tells the arcade that the stick is being pushed to the right is not even being physically pushed...

What's weird is that this had never prevented games and programs to launch... And now it seems it does if I not wiggle the sticks before I launch something...

Does anybody have any idea why this could be happening?